Mathematics: Iq scores are known to be normally distributed. the mean iq score is 100 and the standard deviation is 15. the top 25% of the population (ranked by iq score) have iq’s above what value?

.22, .4, .72. A good way to remember is by adding a 0 on the end of .4....

Iq scores are known to be normally distributed.

kedjenpierrelouis

02.01.2022

110

Step-by-step explanation:

We have been given that the mean IQ score is 100 and the standard deviation is 15.

We will use normal distribution table to solve our given problem.

The top 25% of the population will represent scores greater than 75%.

The z-score corresponding to data greater than 75% is 0.6745.

Upon substituting our given values in z-score formula, we will get:

$z=\frac{x-\mu}{\sigma}$

$0.6745=\frac{x-100}{15}$

$0.6745*15=\frac{x-100}{15}*15$

10.1175=x-100

10.1175+100=x-100+100

110.1175=x

Therefore, the top 25% of the population (ranked by IQ score) have IQ’s above 110.

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