







Significant digits 
20170806 

Pat pose la question : The directions for a problem are: "Solve the problem, expressing your answer
using the correct number of significant figures."
Problem
0.0043 divided by 2.04
Answer before using the correct number of significant figures is
0.002107843
Is the correct number of significant figures the number below?
2107843
Pat Penny Nom lui répond. 





Canada's population as a percentage 
20170511 

bethmarie pose la question : What percentage of the world population (7.5 billion) is Canada's population (36 million).
Thank you very much! Penny Nom lui répond. 





Shooting a ball at a target 
20160216 

Thys pose la question : Hi
I have a problem with the formula that i use .(for programming)
I have looked all over the web to find a solution but no luck.
I have a cannon that shoots a ball at a target
I use this formula to calculate what my initial velocity must be to hit the target
at a angle of 30 degrees and a distance of 15m (the cannon and target position is known)
It works perfectly if both is at same height but if one is higher or lower it miss.
In an example I am working with the range is 30m, the angle is 45 degrees and the target is 10m higher than my position.
Please help
Formula = V0 = √RG / Sin(2α) Harley Weston lui répond. 





Prove that you cannot factor x squared + 5 
20150528 

lily pose la question : the question is: prove that you cannot factor x squared + 5 Robert Dawson lui répond. 





Percentage of water in a soil sample 
20120301 

avi pose la question : what i need is the formula in getting the percentage from gram.
situation:
i need to know how many percent will i declare in getting the moisture of a soil sample
i weighed 2,000 grams of soil before i dried it out in the oven, after few hours the recovery
of the dried out soil is 1,700 grams. How many percent will be the water content?
kindly send me a formula in computing this.
thank u very much! Penny Nom lui répond. 





Designing a tin can 
20110331 

Tina pose la question : A tin can is to have a given capacity. Find the ratio of the height to diameter if the amount of tin ( total surface area) is a minimum. Penny Nom lui répond. 





Multiplication and order 
20110121 

Janet pose la question : IN A MULTIPLICATION SENTENCE BASED ON A DRAWING..IS THERE ANY ORDER FOR THE MULTIPLICAND ANG MULTIPLIER FOR THE ANSWER TO RIGHT? Robert Dawson lui répond. 





[sec^2x]*[sec^2x] 
20101216 

Hari pose la question : [sec^2x]*[sec^2x]=...? Penny Nom lui répond. 





How many zeros? 
20100318 

jeff pose la question : 1 light yr is 6,500 billion miles, the galaxy "Andromeda" is 2,500,000 million light yrs, how many zeros are in this equation ? Robert Dawson lui répond. 





More on millions and billions 
20100311 

julio pose la question : shouldn't the thousands of millions, tens of thousands of millions, and hundreds of thousands of millions be called what they are? technically they are not billions because billions come after 999,999,999,999 . It would sound better to call the numbers by their real name when economists talk about the national deficit besides mathematics is a very precise science that doesn't admit mistakes. Or am I wrong? I know that in other countries is expressed different than here. I have this question to different people and nobody has a "logical" explanation to it. " that's the way is here in the US" does not explain any thing Penny Nom lui répond. 





A circle problem 
20091214 

Fawad pose la question : AP is a tangent at P to a circle centre O, where AP=6cm. The straight line AQC is such that QC= 9cm.
Find the length, in cm of AQ. Chris Fisher lui répond. 





Divide and reduce to lowest terms. 
20090906 

Karen pose la question : Divide and reduce to lowest terms.
Use the cancellation technique as needed
4 2/3 divided by 12
14/3 divided by 12/1 not sure wheer to go from here with the cancellation technique Penny Nom lui répond. 





Paddling downstream 
20090904 

Nicole pose la question : You head downstream on a river in a canoe. You can paddle at 6 km/h and the river is flowing at 2.4 km/h. How far downstream will you be in 55 minutes? Penny Nom lui répond. 





Fred in his canoe 
20090221 

Susan pose la question : Fred paddled for 4 hours with a 7 km/hr current to reach a campsite. The return trip against the same current took 9 hr. Find the speed of Fred's canoe in still water. (Remember to include correct units) Penny Nom lui répond. 





More on infinity and Set Theory 
20090217 

Justin pose la question : I greatly appreciate your help I was just wondering from your previous answer, why doesn't Cantor's cardinal numbers in set theory apply to the limit x>0, y=infinity?
Justin Robert Dawson lui répond. 





Infinity and Set Theory 
20090217 

Justin pose la question : I was just wondering is the limit x>0, y=1/x=infinity, the biggest uncountable infinity according to Cantor's cardinal numbers in set theory?
Justin Robert Dawson lui répond. 





Cantor's cardinality 
20090216 

Justin pose la question : Hello, I was just wondering why the infinity from real numbers is smaller than Beth Two in the context of Cantor's cardinality set theory?
Justin Robert Dawson lui répond. 





Why is the difference between british and american counting? 
20081215 

Muhammad pose la question : Why is the difference between british and american counting?
Example 1 Billion american = 1,000,000,000 but,
1 Billion British = 1,000,000,000,000 Robert Dawson and Harley Weston lui répond. 





A wine decanter 
20081210 

Suzanne pose la question : I am trying to buy a wine decanter for my dad for Christmas. One big
problem I am having shopping online is finding the right size. Wine is sold
by metric ml, with a standard bottle holding 750ml of wine. Decanters are
measured by oz, and the sizes are all over the place, with one site alone
having sizes 25oz, 26 1/2oz, 50oz, 59 1/8oz, and 68oz.
Can you help me with metric conversions so I can figure out how much wine
these decanters hold? Like everybody else, I need this as soon as possible
so I can get it shipped in time for Christmas. (I'm disabled & don't drive, so
online shopping is my only way to get gifts.)
Thanks for your help!
Suzanne Chris Fisher and Robert Dawson lui répond. 





A canal with cross section a semicircle 
20081019 

Connor pose la question : a canal with cross section a semicircle is 10m deep at the centre.
Find an equation for the semicircle and use it to find the depth 4m
from the edge Penny Nom lui répond. 





Distance, time and rate 
20080911 

Pauline pose la question : During the first part of a trip, a canoeist travels 100 miles at a certain speed. The canoeist travels 25 miles on the second part of the trip at a speed 5 mph slower. The total time for the trip is 5 hrs. What was the speed on each part of the trip? Penny Nom lui répond. 





Alpha level 
20080723 

anonymous pose la question : What is the advantage of using an alpha level of .01 versus a level of .05, What is the disadvantage of using a smaller alpha level? Janice Cotcher lui répond. 





Cantor's diagonal argument 
20080126 

David pose la question : Cantor's theory using a diagonal across a list of real numbers to proven uncoutability has always puzzled me.First in base ten, it feels like hocus pocus so I began thinking of the Boolean numbers as truer representations of place value (on,off). Secondly his list was always arbitrary or so I recollect. Therefore, I suggested using a seriesA=.10000....,B=.01000. C=.11000, etc.
Any diagonal is already located among the numbers listed. My only alteration is that since the final digit is always unrepresentably either one or zero, but it must be one or the other, I make an assumption that if x= .abc...1 and y= .abc...2 the only two possibilities and I choose to count F=x+y then then the numbers are countable= Z=sumFi,where I=2+2^2+2^3...
I hope this sketch is enough description, I asked Rudy Rucker more formally but got no mathematical response, someone else gave me some tale about slippery epsilon. What do tyou think of recasting his proofs in more rigorous form?
David French Claude Tardif and Walter Whiteley lui répond. 





What would be the cost of a 10 in * 15 in canvas? 
20071201 

Jasmine pose la question : a 40in *60 in canvas is sold for $60.00 if the price is determined by the cost of the material what would be the cost of a 10 in * 15 in canvas Stephen La Rocque lui répond. 





Countable and uncountable sets 
20070724 

Mac pose la question : Hi, i tried to read few webpages related to the countably infinite and uncountable sets.
Even i read few questions from this forum.
But i am not convinced with this explanation. If you have any good book that
explains this in layman term, please redirect me to that.
1) Can you please explain what is the difference between these too ?
2) How could you say set of Natural number and set of even numbers are countably
infinite ?
N={1,2,3,...} and Even= {2,4,6,...}
When an element in the even set is some 2n, we will map it to 'n'.So
now we have a bigger number(2n) right ?
Sorry, i didn't understand that.
...
Can you please help me out to understand that ? Harley Weston lui répond. 





A statistical difference 
20070703 

a student pose la question : I am writing a paper for a grad class in which I am comparing achievement levels of boys and girls. I have data that shows the average marks for girls and boys in each grade 12 subject for the entire province.
My prof want me to show there is a statistical difference. What do I have to do to show this? I don't have access to the raw data, so don't know the SD. Is there anything I can do mathematically with the data that I have? (I can determine n for each set of data, it ranges between 2400 and about 13000 for each subject area.) Chris Fisher and Harley Weston lui répond. 





Surface area of a cylinder 
20070513 

Nina pose la question : if a cylinder is 23 ft high with a 12 ft radius, how do I find the surface area? Penny Nom lui répond. 





A point inside a circle 
20070504 

edgemitter pose la question : There is a point inside a circle (but not in its center) where two perpendicular secants intersect, dividing the circle into four regions with different area. Calculate the area of the four regions Walter Whiteley lui répond. 





What is the value of csc (2pi/3)? 
20060604 

Kishor pose la question : What is the value of csc (2pi/3)? Stephen La Rocque lui répond. 





A tangent to a parabola 
20051102 

A student pose la question : Find the point on the curve y=x^{2} where the tangent to the curve is parallel to the secant line connecting (1,1) and (2,4) Penny Nom lui répond. 





Cubic feet and imperial gallons 
20051027 

Dave pose la question : What is the volume in cubic feet which is occupied by 1080 Canadian gallons of water? Harley Weston lui répond. 





Different infinities 
20040527 

Plober pose la question : How can I explain to a friend (in a bar, using as a pen and a paper napkin) that the integer's infinity is 'smaller' than the irrationals's one? The demo I tried was that you couldn't match the integers with the real numbers between 0 and 1 (that 0.xxxxx replacing the Nth number from a different one... that demo), but she used my argument >: saying that you can add one to the integer's infinite, and the number I was creating was only one more...
I can't think of any other way, and I KNOW the real's cardinality is greater than the integer's one Claude Tardif and Penny Nom lui répond. 





Acres and square miles 
20040217 

Richard pose la question :
How many acres are in .17 square miles? and How many acres are in .6 square miles?
The two areas I am requesting information about are Vatican City and San Marino, the two smallest countries in the world. If I can transfer the sq. miles into acres , I can relate the size of these countries to our school grounds and the students will better understand their sizes.
Penny Nom lui répond. 





Multiplier and multiplicand 
20031217 

Karen pose la question : The K5 curriculum states that at a grade 5 level students should "understand and use the terms multiplier, multiplicand" The curriculum defines 'multiplicand' as " a number being multiplied by another number. A factor." There is no definition given for 'multiplier'
Question: Define these words are they just other words for 'factors'. If so, how important is it that students use these terms? It would seem like 'factors' would be the better choice of words to use. If multiplcand refers to eg. the first factor in the equation and the 'multiplier' the seond term, (if in fact it does) is this not confusing for students when we teach them that multiplication is commutative? Penny Nom lui répond. 





7,473,000,000 divided by 52000 
20030906 

A student pose la question : I am having trouble with a question. 7,473,000,000 divided by 52000. Our calculater gets 147311.5385. I come up with 143711.53846, and then the number starts to repeat itself Penny Nom lui répond. 





Gallons in a tank 
20030320 

Leslie pose la question : I am trying to figure the liquid gallons in a water tank that is 19" wide by 29.25" long and is 12.25" high. Could you tell me the formula to figure this out. Penny Nom lui répond. 





Sasha's candies 
20030218 

Pat pose la question : Ticktactoe
Sasha and Trudy are playing ticktactoe. Sasha agrees to give trudy two pieces of candy for each game Sasha loses, and Trudy agrees to give Sasha three pieces of candy for each game that Trudy loses. After playing thirty games, Sasha has the amount of candy that he started with. If no ties occurred, how many games did Sasha win? Paul Betts lui répond. 





What is larger than infinity? 
20030112 

Dana pose la question : What is larger than infinity? Claude Tardif and Harley Weston lui répond. 





How many billions equal one trillion? 
20021207 

Ryan and Aylah pose la question : How many billions equal one trillion? We believe that the answer is one thousand times one billion equals one trillion. Please help us with the answer to this question. Penny Nom lui répond. 





Radicals with fractional radicands 
20021111 

A student pose la question : how do I simplify radicals with fractional radicands? ex. 7sqrt(2) + sqrt(50)  2sqrt(18) 10sqrt(3/5)  24sqrt(5/3) 3sqrt(2/9) + 1/2sqrt(32) + sqrt(9/8) Penny Nom lui répond. 





Rounding 27.27 
20021103 

A parent pose la question : If you have a problem 27.27 and you need to round to the first 7 the answer would be 27 Would 27.0 be acceptable as well or is it completely wrong. Penny Nom lui répond. 





For 7 the multiplicand is 143 
20011212 

Cory pose la question : For 7 the multiplicand is 143 I am asked to solve this, if you could help me it would be greatly appreciated! Penny Nom lui répond. 





Gallons 
20011119 

Shawn pose la question : Do we use British or American gallons in Canada? Chris Fisher lui répond. 





A trig identity 
20010727 

Jeff pose la question : prove this identity and show steps tan(x/2+pi/4)=secx+tanx Harley Weston lui répond. 





A sugar cane crop 
20010327 

A student pose la question : a sugar cane farmer harvested only 1/4 of his crop. he sold 2/3 of his harvest to the mill. what fraction of the total crop did he sell. darens recipe for florida fudge calls for 5/8 cup of sugar. if he wants to make only 1/2 of the recipe how much sugar should he use. Penny Nom lui répond. 





The path of a cannonball 
20010115 

A student pose la question : Artillerymen on a hillside are trying to hit a target behind a mountain on the other side of a river. Their cannon is at (x, y) = (3, 250) where x is in kilometers and y is in meters. The target is at (x, y) = (2, 50). In order to avoid hitting the mountain on the other side of the river, the projectile from the cannon must go through the point (x, y) = (1, 410). Write the equation for the problem. Penny Nom lui répond. 





Minimizing the metal in a can 
20000502 

May Thin Zar Han pose la question : A can is to be made to hold 1 L of oil. Find the dimensions that will minimize the cost of the metal to manufacture the can. Harley Weston lui répond. 





Cross multiplication 
20000216 

J E Swinton pose la question : Why does cross multiplication work? How come canceling work? Penny Nom lui répond. 





Two candles 
19991124 

Skip Simpson pose la question : You have two candles the same length. They are lit at the same time. One burns down in 4 hours; the other in 5 hours. How long does it take before one candle is three times the length of the other candle? Walter Whiteley lui répond. 





Cannonballs 
19990127 

Roger King pose la question : How many cannonballs can be stacked in a triangular pyramid? Penny Nom lui répond. 

