1) Option B, which states that the confidence interval size shrank from 0.99 to 0.90, is the right answer.
2) Option D is the best decision. Confidence interval: 0.88
1) A confidence interval in frequentist statistics is a range of estimates for an unknown parameter. A confidence interval is calculated at a specified degree of confidence; the most popular level is 95%, but other levels, such as 90% or 99%, are occasionally used.
Therefore, the correct choice is option B which states that From 0.99 to 0.90 the confidence interval size became smaller
2) In statistics, confidence is another word for probability. If you create a confidence interval, for instance, with a 95% level of confidence, you can be sure that 95 out of 100 times, the estimate will fall between the upper and lower values indicated by the confidence interval.
It can be calculated as:
df=n-1=19
t critical value 0.12 (two tail) = 1.62797
M = 51.5
sM = √(6.842 / 20) = 1.53
μ = M ± Z (sM)
μ = 51.5 ± 1.62797 * 1.53
μ = 51.5 ± 2.49
therefore, CI { 49.01 and 53.99 }
The correct choice is option D. 0.88 confidence interval
To know more about Confidence Interval, refer to this link:
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