Assume the adults have iq scores that are normally distributed with a mean of 105 in a standard deviation of 20 find the probability that a randomly selected adult has an iq less than 145

The correct answer is that the probability of a randomly selected adult has an IQ less than 145 is 97.8%

Step-by-step explanation:

According to the graphic of a standard distribution attached, we have:

68.3% of the population will have an IQ +/- one time the standard deviation plus the mean. It means that 68.3% (Rounding to one decimal place) of the adults will have an IQ between 85 and 125.

95.5% of the population will have an IQ +/- two times the standard deviation plus the mean. It means that 95.5% (Rounding to one decimal place) of the adults will have an IQ between 65 and 145.

The remaining 4.5% of the adults will have either an IQ below 65 or above 145. In this case, we only want to know the percentage below 65 because the question is about the probability of an IQ less than 145. For calculating the percentage of adults that have an IQ less than 65, we use this fraction:

4.5%/2 = 2.3% (Rounding to one decimal)

and we add this percentage to 95.5:

Probability that a randomly selected adult has an IQ less than 145 = 95.5 + 2.3 = 97.8%

Hope the moderator will not delete the answer because I'm uploading a graphic; this graphic is exclusively for academic purposes.

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