Question

If c varies diráctly as (1 + 1) and c= 8, when r = 3, calculate the value ofr when c= 20.

(4marks)​

Answer 1

c = k(r + 1)

8 = k(3 + 1)

8 = 4k

8/4 = k

2 = k

c=2(r + 1)

When c = 20, then

20 = 2(r + 1)

20 = 2r + 2

20 - 2 = 2r

18 = 2r

18/2 = r

9 = r

Therefore, the value of r is 9 when c is 20.