Ten engineers working for start-up companies were asked how long they worked, in hours, per week. the data (in hours) are 70, 45, 55, 60, 65, 55, 55, 60, 50, 55. construct a 90% confidence interval for the population average length of time, in hours, for all engineers at start- ups work per week. (in 2 decimal)

to  

Step-by-step explanation:

Data : 70, 45, 55, 60, 65, 55, 55, 60, 50, 55.

Sample mean =

Sample mean =

Sample mean =

Sample standard deviation  =

Sample standard deviation  =

Sample standard deviation  =

Since n < 30 and population standard deviation is unknown

So we will use t dist.

Confidence interval = 90%

So, significance level =α= 0.1

Degree of freedom = n-1 = 10-1 =9

Now refer the t dist table for t critical

So,

Formula of confidence interval =

Substitute the values

Confidence interval =

Confidence interval = to  

Confidence interval = to  

Hence  a 90% confidence interval for the population average length of time, in hours, for all engineers at start- ups work per week is to  

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