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The area of an odd shaped piece of property |
2003-07-24 |
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Barry pose la question :
What is the formula for figuring the square footage of an odd shaped piece of property?
Penny Nom lui répond. |
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Surface area of a sphere |
2003-07-23 |
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Rob pose la question :
I have a shere with a circumference of 12 feet. What is the total surface area of the shere in square feet and how did you find it?
Penny Nom lui répond. |
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nine digit numbers |
2003-07-23 |
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John pose la question :
With a nine digit number, with each of the nine digits having a possibility of 10 different numbers then what is the total number of possible mathematical variations in the nine digit number. i.e. Social Security numbers have nine digits and if each of the nine digits have a possibility of being any one of ten numbers, i.e. 0,1,2,3,4,5,6,7,8,9. Then what is the formula to calculate the maximum possible number of variations in this nine digit number and what is the mathematical maximum possible number of variations of this nine digit number?
Penny Nom lui répond. |
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Natural logarithms |
2003-07-22 |
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Amanda pose la question :
I'm going into my senior year of high school. I will be taking AP calculus, and my teacher gave us some homework over the summer. However, there are two things that I do not understand how to do. The first is, she wants us to be able to generate a unit circle by hand using 30, 60 and 90 degree triangles. I have used the unit circle in trigonometry, however I was never taught how to draw it. Secondly, I need to know how to do natural logarithms without a calculator. I was not taught how to do this, and the worksheet I was given only showed me how to complete them using a calculator.
Claude Tardif lui répond. |
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A pyramid with its top cut off |
2003-07-21 |
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David pose la question :
What is the name given to a 3D shape that looks like a pyramid with its top cut off?
Penny Nom lui répond. |
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Slope |
2003-07-20 |
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Brian pose la question :
You are placing a pipe 60 feet long at a slope of 1.5%. How would you figure the amount of drop from the inlet of the pipe tot he outlet of the pipe? and what is the answer . If you are trying to keep a shoulder slope of a road between 3/4'' per foot and 11/2'' per foot . If the shoulder is 10 feet wide, how would you figure how much lower should the outside of the shoulder be than the edge of pavement and what is the answer ?
Penny Nom lui répond. |
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|x+3| = -15x |
2003-07-19 |
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Nathan pose la question :
Without the use of trial and error, is there a way of solving for x where |x + 3| = -15x? I know that x = -0.1875, but how do I find whether x + 3 is positive or not if I did not have this information (In other words, how would I solve whether the x-value was -3 or less, or if it was more than -3)?
Claude Tardif and Penny Nom lui répond. |
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"cubic feet" of a refrigerator |
2003-07-16 |
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Ron pose la question :
Is the volume of a home appliance (e.g. fridge or freezer) calculated in a different way? I am planning to replace both my fridge and my freezer but I'm unable to determine what size replacement to get. For example, one company descibes their fridge as being 32"(L) x 30"(W) x 66" (H). I converted those measurements to feet (2.67 x 2.5 x 5.5) and I calculate the fridge to be 36.7 cubic feet. However, the company says the fridge is 18 cf.
Chris Fisher lui répond. |
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Cathy's Clothing |
2003-07-15 |
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Cathy pose la question :
I am supposed to write a practical and useful word problem that would use the following algebriac inequality to solve it: 12x + 25 > 15x + 10. State the quanity that represents x and solve the inequality.
Penny Nom lui répond. |
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Preparing 100ml of a 30% alcohol solution |
2003-07-13 |
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Justin pose la question :
My question is how do you prepare a 100ml of a 30% alcohol solution using 95% alcohol?
Penny Nom lui répond. |
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Sunshine? |
2003-07-11 |
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lori pose la question :
It is noon, your lunch hour, but you cannot go out because there is a terrific hailstorm. Turning on your radio you hear the weathercaster predict that the hail will change to rain and that it will pour all day today. How can you determine whether the sun will be shining in 36 hours?
Claude Tardif lui répond. |
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A problem with lugs |
2003-07-11 |
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Lori pose la question :
A young man's car developed a flat tire as he was driving along a deserted street. He pulled over to the curb and did all the usual things: removed the hub cap, unscrewed the lugs and rested them carefully in the hub cap, jacked up the car. As he was putting the spare tire onto the axle he accidentally kicked the hub cap. The lugs rolled out, and all five of them fell down a nearby grate. Peering through the bars of the grate the man thought that he could see the lugs about 6 feet below in a shallow water puddle. He had a problem. How do you think he solved it?
Penny Nom lui répond. |
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A mixture problem |
2003-07-10 |
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A student pose la question :
Having a problem with word problems. example A chemist mixes a 10% acid solution with a 50% acid solution to form 400mL of a 40% solution. How much of each solution should be used.
Penny Nom lui répond. |
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A triangle in the complex plane |
2003-07-10 |
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Scott pose la question :
The vertices O and A of an EQUILATERAL triangle OAB in the complex plane are located at the origin and 3 + 3i. Find all possible values for the complex number representing the vertex B. Give the location of B in both polar and cartesian form (to 2.d.p)
Penny Nom lui répond. |
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E(X + Y) and V(X + Y) |
2003-07-10 |
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Reuben pose la question :
I'm a teacher trying to find a way to make some stats work from first principles. The topic is expectation algebra and it is for the top age level in high school. By using a set of data I can show how the mean is the same as the expected value ie 2,2,3,4,4 is 15 / 5 = 3 also, 2x0.4+3x0.2+4x0.4=3. I can also show this to work for the variance in the same style but using Sum(x-mean)2/n and the Var(X) version of squaring x then multiplying by the probability ( all this for random independant samples). Now comes the tricky bit.....when I try to show E(X+Y) = E(X) + E(Y) from setting up two data sets I get it to work only if I add each item from X to each item from Y. However, I can't get it to work for V(X+Y)=V(X) + V(Y) from two sets of data. There must be something missing in my knowledge of how the sets are required to add together or my knowledge of expectation algebra. I am familiar with proofs but still want to show my students that the basic formulae work from groups of data whether done the long way or by use of formulae. Can you help please?
Penny Nom lui répond. |
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