Question

If c varies jointly as a cubed and b squared and c=25.6 when a=2 and b=4, find c when a=4 and b=7

Answer 1

Answer:

C=627.2

Step-by-step explanation:

Basically, joint variation is y=kxz. With the provided information, the equation you wanna use is C=k(a)^3(b)^2

Therefore, plug in C for Y, leave K as a variable, and plug in the numbers provided for a and b.

You get 25.6=k(2)^3(4)^2   . When simplified, you get 25.6=128k.

You then divide the 25.6 by the 128 to get .2=k

Now leave C as the variable and plug in the numbers. DON'T FORGET TO CUBE AND SQUARE THE NUMBERS.

It should look like C=(.2)(4)^3(7)^2 , or C=.2(64)(49)

C=627.2  .

Hope this helps, my mistake was forgetting to use the exponents. :)