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The area of my lot |
2003-01-07 |
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Linda pose la question : I have a lot that is 210 feet in the front, 240 feet in the back and the sides each measure 150 feet. How many square feet is this all together and how close to an acre is it? Penny Nom lui répond. |
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Integration of 1/(2+cos(x)) |
2003-01-07 |
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A student pose la question : integral from pi to 0 of dx/(2+cos x) i used the substitution t=tan(x/2) and i ended up with integral from +infinity to 0 of 2dt/(t2+3) which looks like an inverse tan function , and i ended up with sqr(27)/2 pi , which is not the same as my calculator's answer , so i suspct i am doing some thing wrong. can some one tell me where i am going wrong please. Penny Nom lui répond. |
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des conversions de bases différentes |
2003-01-04 |
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Christian pose la question : Je cherche désespérément la (les) règle(s) pour réussir des conversions de bases différentes : de base x vers base y. Claude Tardif lui répond. |
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Mean and median |
2003-01-04 |
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Jan pose la question :
I have a question re: mean and median. I know what the difference is but just need some clarification on when you would use the mean and when you would use the median. Isn't it the case that with a skewed distribution the average (mean) would be higher or lower than the median, but with a normal distribution they would be very similar values? If you have any examples to help explain this that would be greatly appreciated. I am a teacher (of sorts!) and the person who is asking me the question is actually my boss! Penny Nom lui répond. |
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Constructions of polygons |
2003-01-03 |
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Garrett pose la question : Our teacher just finished the constructions unit, and he mentioned briefly about odd sided figures such as pentagons and septagons, only that they're very hard. My question is, how do you draw, with a compass and a straight edge, a pentagon and septagon? Chris Fisher lui répond. |
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Two numbers have a ratio of 5:3 |
2003-01-01 |
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Patricia pose la question : Two numbers have a ratio of 5:3. The larger number is 36 more than half the difference of the two numbers. What are the two numbers? Penny Nom lui répond. |
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Augmented matrix |
2002-12-31 |
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Michelle pose la question : I am trying to augment a matrix so that i can find the values of the variables a, b, and c. For the life of me i can't find a solution to the matrix: 3 -5 2 ' 22 2 3 -1 ' -9 4 3 3 ' 1 I thank you for your help, Michelle Penny Nom lui répond. |
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Successive coefficients in Pascal's Triangle |
2002-12-27 |
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Quincy pose la question : There is a formula connecting any (k+1) successive coefficients in the nth row of the Pascal Triangle with a coefficient in the (n+k)th row. Find this formula Penny Nom and Walter Whiteley lui répond. |
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Averages of Averages |
2002-12-21 |
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Amy pose la question : If in the month of October the % of Payments Received was 80.74% and in November it decreased to 69.36%. Can you take the 80.74-69.36/69.36 to get the % of difference. In otherwords can you take the % of difference when the numbers you are comparing are %'s???? Can you also take an average of an average? For example, average number of payments received in October was 25.00%, average number of payments received November was 50.00%, and the average number of payments received in December was 15.00%. Do you average (25.00%, 50.00% and 15.00%) or do you have to go back to the numbers that calculated the averages. For example, October 25.00% was based on 25 payments being received out of a possible 100. So instead of taking the average of the averages, do you take the average payments and the average customers over the 3 months and calculate the average??? Harley Weston lui répond. |
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20% of 40% of 500 |
2002-12-19 |
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Richard pose la question : What is 20% of 40% of 500? Penny Nom lui répond. |
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The intersection of conics |
2002-12-19 |
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Glenda pose la question : We are studying systems of equations where two conic sections are the two equations that we are solving simultaneously. We were studying the number of solutions that are possible if you have an ellipse and a parabola. We all agree that there can be none, one, two, three or four solutions. The question that the students had for me was whether or not a portion of an ellipse and a parabola can overlap and thereby allow an infinite number of solutions. What should I tell them? Chris Fisher and Harley Weston lui répond. |
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The units digit of 2 to the power of 31921 |
2002-12-18 |
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A student pose la question : If 2 to the power of 31921 is multiplied out, what will be the units digit? Penny Nom lui répond. |
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Odd and even |
2002-12-17 |
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Martin pose la question : I am a graduate engineer trying to teach single digit addition to my 8 year old grand-daughter. My questions follow. Assume a child does not know what multiplication and division are. Assume the child knows how to count from 0 to 10 How do you explain that 2, 4, 6, 8 and 10 are even numbers And 1, 3, 5, 7 and 9 are odd numbers And these three facts? - when you add two even numbers, the answer is even
- when you add two odd numbers, the answer is even
- when you add an even number and an odd number, the answer is odd?
Can all of these be reasoned out, without using the concepts of multiplication or division? Diane Hanson lui répond. |
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Un peu de trigonométrie |
2002-12-16 |
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Hubert pose la question : J'ai 37 ans et les mathématiques sont relativement loin dans ma mémoire, je voudrais savoir s'il existe un méthode pour résoudre une équation du type. a1*cos(x) + a2*sin(x) + a3*cos(2x) + a4*sin(2x) + a5 = 0 Claude Tardif lui répond. |
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Calculations |
2002-12-15 |
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Mahdi pose la question : This problem is rather general, but it usually makes a lot of problems. I almost have no difficulty in math and physics questions, but unfortunately I'm not at all accurate in simple one or two digit calculation. I even sometimes make silly mistakes in simple sums like 7+4=12 or 4+5=11! Is there any effective way to reduce these mistakes? Walter Whiteley lui répond. |
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