Question

A study showed that the average number of hours children in the US watch television each day is 4 hours with a standard deviation of 1.6 hours. If a group of 64 children is selected at random, what is the probability that the average time these children watch television more than 3.5 hours a day?

Answer 1

Solution: - Given - u = 4 --- meon 6 = 1.6 .... standard deviatic n = 64 ... Sample size s be the sample mean , n = 64. 1 Mean (M) = M = 4 So (67) = 5 = 1.6 - 0.2 n 64 I (It is called standard error of the mean) Now, find P ( x > 3.5) P(x23.5) =1-PCX < 3.5) P 21-P * < 3-5-) = y P ( 2 (3.5 - 4 1- 24-2.5 = 1-0.0062 P(x>3.5) - 0.9938 Probability that the average time these children watch television more than 3.5 hours a day in - 0.9938