Answer:
5.1 mph
Step-by-step explanation:
she ran 3 2/5 miles in 2/3 hours.
that is the essential information to solve the problem. everything else is just there to give you "atmosphere" and Shao to confuse you.
the question is simply : what was her speed in mph ?
that means we need to bring the ratio of
3 2/5 miles / 2/3 hours
to 1 hour in the denominator (instead of 2/3 hours).
because we need that to express miles per (one) hour.
so, what do we need to multiply 2/3 with to get 1 (=3/3) ?
2/3 × x = 1
2x = 3
x = 3/2
so, to get 1 hour, we need to multiply the denominator by 3/2.
and to keep the original value of the ratio, we need to multiply also the numerator by the same 3/2.
speed = (3 2/5 miles × 3/2) / (2/3 hours × 3/2) =
= (17/5 miles × 3/2) / (1 hour) = 51/10 miles / 1 hour =
= 5.1 miles / 1 hour = 5.1 mph
