# Population Standard Deviation Essay

CHAPTER 8 AND 9

PROFESSOR JONAS

WIU-RES

BY DEBRA JAMES

CHAPTER 8 1. High temperature in the United States a meteorologist claims that the average of the highest temperatures in the united states in 98. A random sample of 50 cities is selected, and the highest temperatures are recorded. The data are shown. At a=0.05 can the claim be rejected? a=7.7

97, 101, 99, 99, 100, 94, 87, 99, 108, 93, 96, 88, 98, 97,88, 105, 97, 96, 98, 102, 99, 94, 96, 114, 99, 96, 98, 97, 91, 98, 80, 95, 98, 96, 80, 95, 88, 99, 102, 95, 101, 94, 92, 99, 101, 97, 94, 97, 102, 61.

The claim can be rejected; correct answer may be either above 98 or below it.

2. Salaries for Actuaries nationwide graduates entering the actuarial

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2. Communication times - according to the bureau of labor statistics American time use survey married persons spend an average of 8 minutes per day on phones calls, mail and email, while single persons spend an average of 14 minutes per day on these same tasks. Based on the following information is there sufficient evidence to conclude that single persons spend, on average a greater time each day communicating? Use the 0.05 level of significance.

There is not enough information to ... actual average salary. In each of the following ... At the 0.05 level, does this show sufficient evidence to conclude

3. Teachers’ Salaries - a sample of 15 teachers from Rhode Island has an average salary of $35,270, with a standard deviation of $3256. A sample of 30 teachers from New York has an average salary of $29,512, with a standard deviation of $ 1431. Is there a significant difference in teachers’ salaries between the two states? Use a = 0.02. Find the 98% confidence interval for the difference of the two means. H0: μ1 - μ2 = 3000 H1: μ1 - μ2 ≠ 3000 where, H0 is the null hypothesis, d = 3000

For hypothesis testing on two means with known variances:

Δ = [(X1 - X2) - d] / {√[ (σ1² / n1) + (σ2² / n2) ] } where, X1 and X2 are the two sample means σ1 and σ2 are the two sample standard deviations n1 and n2 are the two sample sizes

In this case,

X1 = 35,270