18. A set of data has a sample mean of 65.4 and a standard deviation of 1.2. If the sample size is 45, what is the 99% confidence interval of this data? A. 65.10 and 65.70
B. 65.33 and 65.47
C. 65.05 and 65.75
D. 64.94 and 65.86

Given:

Sample mean = 65.4

Standard deviation = 1.2

Sample size = 45

Confidence level = 99%

To find:

The confidence interval.

Solution:

The formula for confidence interval is

where, is sample mean, z* is confidence value, s is standard deviation and n is sample size.

Confidence value or z-value at 99% = 2.58

Putting the given in the above formula, we get

Therefore, the correct option is D.

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step-by-step explanation:

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add a pic of the graph, then ill edit this "answer" and solve it for you : 3

step-by-step explanation: