Answer :
Mean = 95.125
Variance = 198.90625
Standard deviation = 14.06,
Confidence interval = 95.125 +/- 3.45
To find the 95% confidence interval of the mean score for all bowlers in this league, we need to first calculate the sample mean and sample standard deviation of the given data set.
The sample mean is calculated as follows:
- mean = (96 + 103 + 94 + 105 + 91 + 101 + 99 + 89 + 94 + 91 + 82 + 94 + 97 + 99 + 89 + 107 + 97 + 100 + 96 + 92 + 96 + 95 + 99 + 90 + 84 + 97 + 99 + 87 + 102 + 92 + 91 + 90 + 88 + 103 + 94 + 90 + 98 + 91 + 87) / 40
mean = 95.125
The sample standard deviation is calculated as follows:
First, we need to calculate the variance of the data set, which is done by taking the sum of the squared differences between each score and the mean, and dividing by the sample size minus 1:
- variance = ((96 - 95.125)^2 + (103 - 95.125)^2 + (94 - 95.125)^2 + (105 - 95.125)^2 + (91 - 95.125)^2 + (101 - 95.125)^2 + (99 - 95.125)^2 + (89 - 95.125)^2 + (94 - 95.125)^2 + (91 - 95.125)^2 + (82 - 95.125)^2 + (94 - 95.125)^2 + (97 - 95.125)^2 + (99 - 95.125)^2 + (89 - 95.125)^2 + (107 - 95.125)^2 + (97 - 95.125)^2 + (100 - 95.125)^2 + (96 - 95.125)^2 + (92 - 95.125)^2 + (96 - 95.125)^2 + (95 - 95.125)^2 + (99 - 95.125)^2 + (90 - 95.125)^2 + (84 - 95.125)^2 + (97 - 95.125)^2 + (99 - 95.125)^2 + (87 - 95.125)^2 + (102 - 95.125)^2 + (92 - 95.125)^2 + (91 - 95.125)^2 + (90 - 95.125)^2 + (88 - 95.125)^2 + (103 - 95.125)^2 + (94 - 95.125)^2 + (90 - 95.125)^2 + (98 - 95.125)^2 + (91 - 95.125)^2 + (87 - 95.125)^2) / (40 - 1)
variance = 198.90625
The sample standard deviation is then the square root of the variance:
standard deviation = sqrt(198.90625)
standard deviation = 14.06
Now that we have the sample mean and sample standard deviation, we can use these values to calculate the 95% confidence interval of the mean score for all bowlers in this league.
We can use the following formula to calculate the confidence interval:
confidence interval = mean +/- (1.96 * (standard deviation / sqrt(sample size)))
Substituting in the values we calculated above, we get:
confidence interval = 95.125 +/- (1.96 * (14.06 / sqrt(40)))
Hence , confidence interval = 95.125 +/- 3.45
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