Hypothesis tests & confidence intervals worksheet with answers

Free printable Hypothesis tests & confidence intervals worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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Name: ____________________ Date: ____________

1.Easy

A company claims that a proportion of 0.25 of its customers are satisfied. In a random survey of 100 customers, 33 say they are satisfied. Find the test statistic z for H₀: p = 0.25.

p₀ = 0.25n = 100x = 33

z =

2.Easy

A machine is supposed to fill bottles with 75 mL on average. The standard deviation is known to be 12 mL. A sample of 36 bottles has a mean of 77.4 mL. Find the test statistic z for H₀: μ = 75.

μ₀ = 75 mLx̄ = 77.4 mLσ = 12 mLn = 36

z =

3.Medium

7 employees take a typing test before and after a training course. For each person the difference d = after − before (words per minute) is recorded. The mean difference is 9.05 and the standard deviation of the differences is 11.4. Find the paired test statistic t for H₀: μ_d = 0.

n = 7d̄ = 9.05s_d = 11.4

t =

4.Medium

A sample of 81 students has a mean score of 74.02 and a sample standard deviation of 4. Find the test statistic t for H₀: μ = 75.

μ₀ = 75x̄ = 74.02s = 4n = 81

t =

5.Hard

A sample of 64 measurements has mean 500.6. The population standard deviation is 12. Find the lower limit L of the 95% confidence interval for the mean.

x̄ = 500.6σ = 12n = 6495%

L =

6.Hard

A sample of 49 measurements has mean 101.1. The population standard deviation is 5. Find the upper limit U of the 99% confidence interval for the mean.

x̄ = 101.1σ = 5n = 4999%

U =

Answer key

1. z = 1.848
2. z = 1.2
3. t = 2.1
4. t = −2.205
5. L = 497.7
6. U = 102.9

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