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The Welsh Adult Intelligence Scale is a common ‘IQ test’ for adults. The distribution of WAIS scores for people over 16 years of age is approximately normal with mean 100 and standard deviation 15.
(a) What is the probability that a randomly chosen individual has a WAIS score of 105 or higher?
(b) What are the mean and standard deviation of the average WAIS score x for random sample of 60 people?
(c) What is the probability that the average WAIS score of a random sample of 60 people is 105 or higher?
(a) What is the probability that a randomly chosen individual has a WAIS score of 105 or higher?
(b) What are the mean and standard deviation of the average WAIS score x for random sample of 60 people?
(c) What is the probability that the average WAIS score of a random sample of 60 people is 105 or higher?