Question

Sandi tracks her calories burned during water aerobics class. The number of calories she burns is expressed by the function c(t) = 350t, where t is the number of hours spent doing water aerobics.
To burn more calories, Sandi wears ankle weights during her class. The number of calories she burns while wearing ankle weights is expressed by the function b(c) = 1.2c, where c is the number of calories burned doing water aerobics without weights.

Which of the following composite functions expresses the calories, as a function of time, Sandi burns while doing water aerobics with ankle weights?

A b[c(t)] = 351.2t A B C OR D?
B b[c(t)] = 420t
C c[b(t)] = 351.2t
D c[b(t)] = 420t

Answer 1

We have c(t) = 350t and b(c) = 12c

The composite function that expresses the calories as function of time is given by

b[c(t)] = 12[350t]
b[c(t)] = 420t

Correct answer: B