A salesperson who had been driving at a speed of 100 kilometers per hour slowed down

[BTGModeratorVI]

A salesperson who had been driving at a speed of 100 kilometers per hour slowed down to a speed of 47 kilometers per hour. Approximately how many miles per hour was the speed reduced?
(1 kilometer ≈ 0.625 mile)

A. 29
B. 33
C. 53
D. 63
E. 75

Answer: B
Source: Official guide

[Brent@GMATPrepNow]

A salesperson who had been driving at a speed of 100 kilometers per hour slowed down to a speed of 47 kilometers per hour. Approximately how many miles per hour was the speed reduced?
(1 kilometer ≈ 0.625 mile)

A. 29
B. 33
C. 53
D. 63
E. 75

Answer: B
Source: Official guide

A salesperson who had been driving at a speed of 100 kilometers per hour slowed down to a speed of 47 kilometers per hour.
Reduction in speed = 100 - 47 = 53 kilometers per hour
We can use equivalent ratios to convert 53 kilometers per hour to miles per hour.

We are told that 1 kilometer ≈ 0.625 miles

So, if we use the ratio kilometers/miles, we can express the relationship as: kilometers/miles = 1/0.625
Let x = the desired speed (in mph)
We can now write: 1/0.625 = 53/x
Cross multiply to get: 1x = (53)(0.625) ≈ 33 mph

Answer: B

Cheers,
Brent