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Associative or commutative? |
2007-08-24 |
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From Terry:
5*(7*2)=(7*5)*2 Is this associative property or commutative ??? Both?
Answered by Penny Nom. |
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A frustum of a right pyramid |
2007-08-24 |
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From Andrew:
Find the volume of a frustum of a right pyramid whose lower base is a square with a side 5 in., whose upper base is a square with a side 3in., and whose altitude is 12 in. Round your answer to the nearest whole number.
A. 47cu in. C. 226 cu in.
B. 196 cu in. D. 1036 cu in.
Answered by Stephen la Rocque. |
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More on a percentage question |
2007-08-23 |
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From Dee:
In a previous question, you answered:
"What percentage of $34.51 is $10.71?
I translate this English statement into a mathematical statement (equation) using the following
"what" is the unknown, call it x
"percent" is per-one-hundred, that is over 100
"of" is multiplication
"is" is the verb, which in an equation is the equal sign
Thus the English statement above becomes
x/100 $34.51 = $10.71
Solving for x yields
x = 31.03
Hence the gross profit is 31% of your selling price."
How did you solve for 'x'
Answered by Penny Nom. |
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Four fours |
2007-08-23 |
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From Belinda:
My son came home with a math question that I can figure out. He needs to use only the number 4 and only four 4's, no less no more.
The problems need the answers 11,13,14,and 18. He can use any mathematical sign except square root. He's been able to get all but these
so far and I've worked them, but can't come up with the problems. Can anyone help?
Answered by Stephen la Rocque. |
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How many three button codes are possible? |
2007-08-23 |
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From kim:
A home security device has ten buttons and is disarmed by pushing three buttons in sequence. How many three button codes are possible if each button can be pushed more than once in the code?
Answered by Stephen la Rocque. |
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Parametric equations |
2007-08-22 |
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From will:
Graph and make a sketch of x = ysquared - 6y + 11 in parametric mode (hint: you need to come up with 2 parametric equations).
i have already figured out that the cartesian form of the parametrics will be y = +/- sqroot(x-2) + 3, but i do not know how to produce 2 parametric equations from this.
Answered by Penny Nom. |
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32,648 square footage = how much land? |
2007-08-22 |
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From Elizabeth:
1. What amount of Land = an acre?
2. 32,648 square footage = how much land?
Answered by Penny Nom. |
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Which is more, 1.25 grams or 4.7 ml? |
2007-08-22 |
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From jenni:
Which is more? 1.25 grams or 4.7 ml
Answered by Penny Nom. |
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65 grams =_____?mg |
2007-08-22 |
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From Quan:
65 grams = _____?mg
Answered by Penny Nom. |
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Converting a repeating decimal to a common fraction |
2007-08-22 |
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From isabelle:
how do you turn 6.333... into a fraction in simplest form?
Answered by Stephen La Rocque and Penny Nom. |
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Where do you use trigonometry? |
2007-08-21 |
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From jenny:
where do you use trigonometry besides architecture and engineering?
Answered by Stephen La Rocque. |
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-31=6w-7 |
2007-08-21 |
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From Shaneka:
-31=6w-7
Answered by Penny Nom. |
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More on the sixth degree equation |
2007-08-21 |
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From Farzan:
Equation 1 :
(R + (6.67*5.98*10^13/((R^2)*2)))^2 - (R^2) = (7.27*(10^-5)*R)^2
Equation 2 :
(6.67*5.98*10^13/(R^2*2))^2 + 6.67*5.98*10^13/R = (7.27*10^-5*R)^2
As you see if we expand the left part of the first equation and simplify, the
equations become same, but these two equations have different answers in my
math software.The first one has 3 amounts for R, but the second one has 6
amounts. Why are the answers different ?
Answered by Stephen La Rocque. |
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Two coplanar lines |
2007-08-21 |
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From Robin:
I am going two show that the two lines are coplanar:
(x-5)/4=(y-7)/4=-(z+3)/5
(x-8)/7=y-4=(z-5)/3
I know I have to find a point that lie on both lines, but dont really get it.
Answered by Stephen La Rocque and Penny Nom. |
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Ten workers perform one job in five days |
2007-08-21 |
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From Kenneth:
If ten workers perform one job in 5 days, one person performs one job in how many days?
Here is the calculation that I used:
(10 workers X 1 job X 5 days)/(1 person X 1 job X ? days)
The above equals 50/1, and the answer is 50 days because 50/1 = 50. In this calculation I can determine any number of workers or days if the number of jobs remains the same as that in the group of factors from the numerator (10 workers X 1 job X 5 days), that is 1 job. Here is another example to help clarify: (10 workers X 1 job X 5 days)/(? workers X 1 job X 10 days) This equals 50/10. The answer is 5 workers. So, if 10 workers can perform 1 job in 5 days, 5 workers can perform 1 job in 10 days.
Now, if I replace "1 job" from (10 workers X 1 job X 5 days) with a different number, for example, 4 jobs, this amount will prevent the calculation from producing the correct answer.
Here is an example: (10 workers X 1 job X 5 days)/(10 workers X 4 jobs X ? days) Mathematically, the calculation works, but the answer, 1.25 days, is not correct, if I'm not mistaken. If 10 workers can perform 1 job in 5 days, they cannot, by working at the same rate, perform 4 jobs in 1.25 days.
Can you explain, with a simple explanation, why the number representing the jobs in this calculation needs to be the same in the group of factors in both the numerator and in the denominator in order to provide the correct answer?
Answered by Harley Weston. |
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