S is directly proportional to M^3. It is given that S=36 for a certain value of M. Find the value of S when this value of M is

Question

(a) doubled
(b) reduced by 40%

Answer 1

S=k*M^3

so if M is doubled, S must go up by 8 (2^3)

so if M is changed to .4, S must be down by .6^3=.216

answers:
a) 36*8
b) 36*.216