Question

Suppose that easy financial aid a lot of text book stipend by claiming that the average textbook at Vesey bookstore cost $80.87. Do you want to test this claim. The Noel and alternative hypothesis in symbols would be

In a survey, 11 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $33 and standard deviation of $2. Construct a confidence interval at a 80% confidence level. Give your answers to one decimal place. I Question Help: Message instructor Submit Question 0 Type here to search o o e C . esc is IS 2 3 4 5 6 7.

Answer 1

Solution :

=> from the given information,

Null and Alternative hypothesis :

H0 : μ = 80.87

H1 : μ ≠ 80.87

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Solution :

Given that n = 11, mean x-bar = 33 , standard deviation s = 2

=> df = n - 1 = 10

=> for 80% confidence level, t = 1.372

=> A 80% confidence interval of the mean is

=> x-bar +/- t*s/sqrt(n)

=> 33 +/- 1.372*2/sqrt(11)

=> 33 +/- 0.8273

=> 33.0 +/- 0.8 (rounded)