find the 90% confidence interval

Question

How many hours per week do gamers play video games? A simple random sample of 84 U.S. gamers age 13 or older are given below.

Sample Data

a.) Find a 90% confidence interval for the population average time per week a gamer 13 or older plays video games. (Round answers to two decimal place.)

margin of error:  hr/wk

lower limit:  hr/wk

upper limit:  hr/wk

b.) What conditions were met so the results are valid? (Select all that apply.)

1. time per week a gamer 13 or older plays video games needs to be uniformly distributed
2. time per week a gamer 13 or older plays video games needs to be normally distributed
3. simple random sample
4. large enough sample size n
5. � is known
6. � is unknown
7. systematic sampling

c.) Interpret: We are % confident that the population mean time per week a gamer 13 or older plays video games is between  hours/week and  hours/week .

Answer 1

Hi Hazel,

Sadly the sample data isn't linked, so I can't use your exact data, but the formula for a 90% Confidence interval is: CI = Mean +/- 1.65*SE

So, for your data, calculate the mean. Then, calculate the standard Deviation. To get standard Error, divide Standard Deviation by the Square Root of the sample size.

Example: Mean = 5, Standard Dev = 4, Sample Size (n) = 16

Z for 90% Confidence Interval = 1.65

Standard Error = 4/Sqrt(16) = 4/4 = 1

CI Upper = 5 + 1.65*1 = 6.65

CI Lower = 5 - 1.65*1 = 3.35

CI 90 = [3.35 - 6.65]

Hope this helps, good luck!