Question

If b is inversely proportional to c, and b is 5 when c is 12, find b when c = 20.

A. b = 60
B. b = 4
C. b = 15
D. b = 3

Answer 1

b=3

Explanation:

If b is inversely proportional to c then

`b=(k)/(c)`

b is 5 when c is 12, means...

`5=(k)/(12)`

From where we obtain the value of k, the constant needed, which is equals to 5*12=60

Now... to find b when c=20, is just a matter of using our known variables.

`b=(60)/(20)=3`