For a sample of 54 discount brokers the average price of a $5,000 trade was $33.77 and the standard deviation was $15. Construct a 90% confidence interval and enter the upper bound for the interval. Hint, your answer should be larger than the one for the previous question since they begin with the same summary data. (Answer to two decimal places and do not include a $ sign).

Question

Business

Frank

19 July, 23:44

For a sample of 54 discount brokers the average price of a $5,000 trade was $33.77 and the standard deviation was $15. Construct a 90% confidence interval and enter the upper bound for the interval. Hint, your answer should be larger than the one for the previous question since they begin with the same summary data. (Answer to two decimal places and do not include a $ sign).

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Answers (1)

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Neil Valenzuela · Answer 1

Margin error=3.3574

Confidence Interval = 37.1274

Explanation:

For confidence level 1-a

(90/100) = 0.9

1-0.9 = 0.1

za/2 = 0.1/2

0.05

Therefore using the z-score table

0.05 = 1.645

The margin error is:

1.645*15/Sqare root of 54

=1.645*2.041

=3.3574

Confidence Interval

33.77 - 3.3574 = 30.4126

33.77+3.3574 = 37.1274