A random sample of 19 subjects was asked to perform a given task. The time in seconds it took each of them to complete the task is recorded below. 43, 28, 50, 34, 31, 43, 32, 48, 46, 28, 45, 35, 36, 32, 28, 42, 31, 42, 33 If we assume that the completion times are normally distributed, find a 90% confidence interval for the true mean completion time for this task. Give the lower limit and upper limit of the 90% confidence interval. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place.  Upper limit: Lower limit:

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A random sample of 19 subjects was asked to perform a given task. The time in seconds it took each of them to complete the task is recorded below.

43, 28, 50, 34, 31, 43, 32, 48, 46, 28, 45, 35, 36, 32, 28, 42, 31, 42, 33

If we assume that the completion times are normally distributed, find a 90% confidence interval for the true mean completion time for this task. Give the lower limit and upper limit of the 90% confidence interval.

Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. 

Upper limit:

Lower limit:

Expert Solution
Step 1: we determine given and find mean and sd.

Let,

x: 43, 28, 50, 34, 31, 43, 32, 48, 46, 28, 45, 35, 36, 32, 28, 42, 31, 42, 33

x with bar on top equals fraction numerator sum for i equals 1 of x over denominator n end fraction
space stack x space with bar on top equals fraction numerator 43 plus space 28 plus space 50 plus space 34 plus space 31 plus space 43 plus space 32 plus space 48 plus space 46 plus space 28 plus space 45 plus space 35 plus space 36 plus space 32 plus space 28 plus space 42 plus 31 plus space 42 plus 33 over denominator 19 end fraction
space x with bar on top space equals 707 over 19
x with bar on top space equals space 37.21

Statistics homework question answer, step 1, image 1

s equals square root of fraction numerator open parentheses x minus x with bar on top close parentheses squared over denominator n minus 1 end fraction end root
s equals square root of fraction numerator 917.634 over denominator 19 minus 1 end fraction end root
s equals 7.27


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