Question

Children between the ages of 2 and 5 watch an average of 25 hours of television per week. Assume the variable is normally distributed and the standard deviation is 3 hours. If 20 children between the ages of 2 and 5 are randomly selected, find the probability that the mean of the number of hours they watch television will be greater than 26.3 hours.

_________ Round your answer to 4 decimal places.

Answer 1

Solution :

Given that ,

mean = = 25

standard deviation = = 3

n = 20

= 25

= / n = 3 / 20 = 0.67

P( >26.3 ) = 1 - P( < 26.3)

= 1 - P[( - ) / < (26.3-25) / 0.67]

= 1 - P(z < 1.94)

Using z table

= 1 - 0.9738

= 0.0262

probability=0.0262