Question

m is directly proportional to cube r
when r=4 and m=160
work out the value of r when m=540

Answer 1

m directly proportional to r³, then

m1/m2 = r1³/r2³

m2 = 160, m1 =540

r2 = 4, r1 = x

540/160 = x³/4³

x³ = 540/160 ×4³ =216 = 6³

x =6

value of r when m =540 is 6