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Salaries for teachers in a particular elementary school district are normally distributed with a mean of\(44,000and a standard deviation of \)6,500. We randomly survey ten teachers from that district.

a. Find the90thpercentile for an individual teacher’s salary.

b. Find the 90thpercentile for the average teacher’s salary.

Short Answer

Expert verified

(a)90thpercentile for individual teacher's salary is .

(b)90thpercentile for average teacher's salary is $46634.20.

Step by step solution

01

Part (a) Step 1: Given information 

Given in the question that, Salaries for teachers in a particular elementary school district are normally distributed with a mean of $44,000 and a standard deviation of $6,500. We randomly survey ten teachers from that district.

02

Part (a) Step 2: Explanation

According to the information provided, teacher salaries in a certain elementary school are normally distributed, with a mean of $44000and a standard deviation of $6500, and a random poll of 10instructors from that district is conducted.

Let Xrepresent the teacher's salary, which is normally distributed.

X~N($44000,$6500)

Use a Ti-83 calculator to get thelocalid="1648396959689" 90thpercentile for individual teacher salaries. To do so, go tolocalid="1648396972586" 2nd, then DISTR, then scroll down to the invNorm option and fill in the required information. After that, press the calculator's ENTER key to get the desired result. The following is a screenshot:

03

Part (b) Step 1: Given information

Given in the question that, Salaries for teachers in a particular elementary school district are normally distributed with a mean of $44,000 and a standard deviation of $6,500. We randomly survey ten teachers from that district.

04

Part (b) Step 2: Explanation

According to the supplied details, salaries for teachers in a particular elementary school are normally distributed with mean $44000and standard deviation $6500, and a random survey of 10teachers is done from that district.

Let denotes the average salary of 10randomly chosen teachers from the district.

X¯~Nμ,σn

~N44000,650010

~N(44000,2055.48)

To calculate90thpercentile for average teacher salary, use Ti-83calculator. For this, click on 2nd, then DISTR and then scroll down to the invNorm option and enter the provided details. After this, click on ENTER button of calculator to have the desired result. The screenshot is given as below:

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