A bicyclist begins a race at a constant rate of 10 miles per hour, slowing down by 1 mile per hour every half-hour. How

[M7MBA]

A bicyclist begins a race at a constant rate of 10 miles per hour, slowing down by 1 mile per hour every half-hour. How many miles has the bicyclist traveled after exactly 2.5 hours?

A) 22.5
B) 20
C) 19
D) 17
E) 12.5

Answer: B

Source: Princeton Review

[swerve]

A bicyclist begins a race at a constant rate of 10 miles per hour, slowing down by 1 mile per hour every half-hour. How many miles has the bicyclist traveled after exactly 2.5 hours?

A) 22.5
B) 20
C) 19
D) 17
E) 12.5

Answer: B

Source: Princeton Review

We know, Distance=Speed\(\cdot\)time

Here , total distance traveled \(=\) sum of the distances at \(5\) intervals \(=0.5\cdot(10+9+8+7+6)=0.5\cdot 40=20\) miles.

Thereofre, B