If we are comparing two populations, one where n = 15 and one where n = 45.. What is the proper value for degrees of freedom?

a. 30

b. 29

c. 14

d. 44

A research firm collects a random sample of 1500 customers at a particular store. The sample shows that the average transaction for the sample was $138 with a standard deviation of $43. Calculate a 95% confidence interval for the mean.

Of those 1500 customers, 673 of them used coupons. Calculate a 95% confidence interval for the percentage of customers who used coupons when making a purchase.

The last time we looked at prices of 8 pairs of Payless sandals to find that:
1. The average price for each pair is $20.625
2. Standard deviation is $ 6.3

Suppose in our school, each person on average spends $25 on a pair of sandal. Is the price of sandals at Payless significantly cheaper than the average price we pay? (Use hypothesis testing with 95% level of confidence)

finding a sample size

I want a confidence interval of 95% with a population size of p+-.o5
where p+-z{[P(1-P)/n]^(1/2)} which can also be written as n=[z^2[P(1-P)]/m^2

Find the Standard Error between males and females for hours spent at the gym per week.

Males - Females

Nm = 20 Nf=18

Sample Mean = 8 Sample Mean = 6

Standard Deviation = 3.5 Standard Deviation = 2.5

Hypothesis Testing

Use hypothesis testing in the following problem to determine whether the null hypothesis is correct.

n = 100
mean = 46
standard deviation = 12

Null hypothesis M = 50
Alternate M does not = 50

use a confidence level of 95%

Z Values for Confidence Levels

What are the Z values for the following confidence levels?

1) 90%
2) 95%
3) 99%