Question

The average on a statistics test was 76 with a standard deviation of 11. If the test scores are normally distributed, find the probability that the mean score of 36 randomly selected students is between greater than 81. *

Answer 1

Solution :

= / n = 11 / 36 = 1.8333

P( > 81) = 1 - P( < 81)

= 1 - P[( - ) / < (81 - 76) / 1.8333]

= 1 - P(z < 2.73)

= 1 - 0.9968

= 0.0032

Probability = 0.0032