Question

The weights of the fish in a certain lake are normally distributed with a mean of 9.4 lb and a standard deviation of 2.3. If 42 fish are randomly selected, what is the probability that the mean weight will be more than 9.7 lb?

Answer 1

Solution :

Given that ,

mean = = 9.4

standard deviation = = 2.3

= / n = 2.3 / 42 = 0.3549

P( > 9.7) = 1 - P( < 9.7 )

= 1 - P[( - ) / < (9.7 -9.4)/0.3549 ]

= 1 - P(z < 0.85 )

= 0.8023 , Probability = 0.8023