A police radar gun is used to measure the speeds of cars on a highway. The speeds of cars are normally distributed with a mean of 55 mi/he and a standard deviation of 5 mi/hr. Roughly what percentage of cars are driving less than 45 mi/hr ? Round to the nearest tenth of percent .
A. 95.0%
B. 2.5%
C. 5.0%
D. 18.0%