Example Problem $10\mathrm{.}2$

Interstate Safety Corridors are established on certain roadways with a propensity for strong

cross winds, blowing dust, and frequent fatal accidents.

A driver is expected to turn on the headlights and pay special attention to the posted speed

limit in these corridors.

In one such Safety Corridor in northern New Mexico, the posted speed limit is $75$ miles per

hour.

The Department of Public Safety set up a radar checkpoint and the actual speed of $36$

vehicles that passed the checkpoint is shown in the Table below.

Actual speeds of cars in Safety Corridor

Calculate the mean, variance and the standard deviation, using the alternate equation of Standard

deviation.