The probability that a randomly selected adult has an iq between 89 and 121 is 0.80.
To find the probability that a randomly selected adult has an iq between 89 and 121:
Because we assume that these data are normally distributed in the adult population, we can answer this question by first converting our given scores to a standard normal distribution (a set of z-scores):
Therefore, the probability that a randomly selected adult has an IQ between 89 and 121 is 0.80.
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The correct question is given below:
Assume that adults have IQ scores that are normally distributed with a mean of 105 and a standard deviation of 20. Find the probability that a randomly selected adult has an IQ between 89 and 121