Answer:
The 95% Confidence Interval for the difference between the two population mean completion times =
(0.081, 1.919)
Step-by-step explanation:
Confidence Interval for difference between two means =
μ1 -μ2 ± z × √ σ²1/n1 + σ²2/n2
Where
μ1 = mean 1 = 12 mins
σ1 = Standard deviation 1 = 2 mins
n1 = 100
μ2= mean 2 = 11 mins
σ2 = Standard deviation 2 = 3 mins
n1 = 50
z score for 95% confidence interval = 1.96
μ1 -μ2 ± z × √ σ²1/n1 + σ²2/n2
= 12 - 11 ± 1.96 × √2²/100 + 3²/50
= 1 ± 1.96 × √4/100 + 9/50
= 1 ± 1.96 × √0.04 + 0.18
= 1 ± 1.96 × √0.22
= 1 ± 1.96 × 0.469041576
= 1 ± 0.9193214889
Confidence Interval
= 1 - 0.9193214889
= 0.0806785111
≈ 0.081
1 + 0.9193214889
= 1.9193214889
≈ 1.919
Therefore, the 95% Confidence Interval for the difference between the two population mean completion times =
(0.081, 1.919)
