Question

The average life expectancy of Canadian women is 75 years, and is normally distributed. The standard deviation is known to be 7 years. If a random sample od 49 women is taken, what is the probability that the average age of the sample of women is:

Between 73.5 and 76 years?
Between 72 and 74 years?
Less than 72.7 years?

Answer 1

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z scores.

Z = (score-mean)/SEm

SEm = SD/√n

Answer 2

73.5-76=2.5/7 = 0.357