Question

Assume that adults have IQ scores that are normally distributed with a mean of 104.3 and a standard deviation 18.4. Find the first quartile Q,, which is the lo score separating the bottom 25% from the top 75%. (Hint: Draw a graph)The first quartie is(Type an integer or decimal rounded to one decimal place as needed)

Answer 1

Given:

`mean,\text{ }\mu=104.3\text{ and standard deviation, }\sigma=18.4.`

Required:

We need to find the first quartile Q1.

Step-by-step explanation:

Consider the formula to find the first quartile Q1.

`Q1=\mu-(0.675)\sigma`

`Q3=\mu+(0.675)\sigma`

`Substitute\text{ }\mu=104.3\text{ and }\sigma=18.4\text{ in the formula }Q1=\mu-(0.675)\sigma.`

`Q1=104.3-(0.675)(18.4)`

`Q1=91.88`

`Q1=91.9`

Final answer:

The first quartile is 91.9.