a.
To find: The 95% confidence interval for the mean reading test score and interpret it.
a.
Answer to Problem 70E
The confidence interval is (237.163, 242.837).
Explanation of Solution
Given:
Sample mean
Sample standard deviation
Formula used:
The formula to compute the t - confidence interval for population mean is:
Calculation:
Here, t -confidence interval is to be used because population standard deviation is unknown.
The obtained excel output is:
Thus, the required confidence interval is (237.163, 242.837)
Interpretation:
There is 99% probability that the mean reading score lies between 237.163 and 242.837.
b.
To explain: Whether it could be concluded that the mean reading score is less than the basic level score, that is, 243
b.
Answer to Problem 70E
Yes, it could be concluded the mean reading score is less than the basic level score.
Explanation of Solution
From the above, it is known that the confidence interval is (237.163, 242.837). Since, the mean reading score lies between 237.163 and 242.837. Thus, it could be concluded that the mean reading score is less than the basic level score
Chapter 8 Solutions
PRACTICE OF STATISTICS F/AP EXAM
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