Question

A car's speedometer has a percent error of 5%. The speedometer currently shows that the car is traveling at a speed of 60 mph.

Which statement describes what the actual speed of the car could be?


The actual speed of the car is either 30 mph or 90 mph.

The actual speed of the car is either 55 mph or 65 mph.

The actual speed of the car is either 57 mph or 63 mph.

The actual speed of the car is either 58 mph or 62 mph.

Answer 1

The actual speed of the car is either 57 mph or 63 mph.

Explanation:

Note that 5% of 60 mph is 3 mph. Thus, the actual speed of the car is between (60 - 3) mph and (60 + 3) mph, or between 57 mph and 63 mph.

The third answer choice is the correct one.

Answer 2

The actual speed of the car is either 57 mph or 63 mph.

Explanation:

First Calculate 0.05*60=3

The limit could either be

60-3=57 Or 60+3=63

57 mph of 63 mph