Question

A is directly proportional to B when A = 12, B = 3 a) find a formula for A in terms of B b) find the value of A when B = 5 c) find the value of B when A = 36

Answer 1

a) A = kB

b) 20

c) 9

Explanation:

A is directly proportional to B when A = 12, B = 3

a) find a formula for A in terms of B

A ∝ B

A = kB

Where k is constant of proportionality

when A = 12, B = 3

12 = 3k

k = 12/3

k = 4

b) find the value of A when B = 5

A = kB

k = 4

A = 4 × 5

A = 20

c) find the value of B when A = 36

k = 4

A = kB

B = A/k

B = 36/4

B = 9