Question

Find an equation of joint variation. Then solve for the missing value.

a varies jointly as b and c.
One set of values is a = 2.4, b = 0.6, and c = 0.8.
Find a when b = 0.4 and c = 0.4.
a = 0.8
a = 1.2
a = 0.032
a = 1.6
Click on the correct answer

Answer 1

a = 0.8

Explanation:

a varies jointly as b and c.

This means that a can be written as a constant k multiplied by b multiplied by c, that is:

`a = kbc`

One set of values is a = 2.4, b = 0.6, and c = 0.8.

We use this to find the value of k:

`2.4 = k(0.8)(0.6)`

`0.48k = 2.4`

`k = (2.4)/(0.48)`

`k = 5`

So

`a = 5bc`

Find a when b = 0.4 and c = 0.4.

`a = 5bc = 5(0.4)(0.4) = 5(0.16) = 0.80`

The answer is a = 0.8.