John Beale of Stanford, CA, recorded the speeds of cars driving past his house, where the speed limit read 20 mph. The mean of 100 readings was 23.84 mph with a standard deviation of 3.56 mph. (He actually recorded every car for a two-month period.)
How many standard deviations from the mean would a car going under the speed limit be?
A) -2
B) -1.08
C) 1.08
D) 2