Add an intersection with a red light times are normally distributed with a mean time of three minutes and a standard deviation of .25 minutes approximately what percent of my lights last between 2.5 and 3.5 minutes

2.5 and 3.5 are two standard deviations from the mean, since 2.5 = 3 - 2(0.25) and 3.5 = 3+2(0.25).

The empirical (68-95-99.7) rule says that approximately 95% of a normal distribution falls within two standard deviations of the mean.

other answer is correct. i had used the radius of the radius somehow. a website:

7/2

(decimal: 3.5)

welcome ; )

step-by-step explanation: