31 - The phones produced in factory A have a lifespan of 2900 days and a standard deviation of 100 days. The phones produced in factory B have a lifespan of 2600 days and a standard deviation of 150...

31 - The phones produced in factory A have a lifespan of 2900 days and a standard deviation of 100 days. The phones produced in factory B have a lifespan of 2600 days and a standard deviation of 150 days. A sample of 50 telephones was taken from factories A and B. What would be the standard error of the difference between the sample averages of the lifetimes of the phones?
A) 25.49

B) 74.28

C) 29.55

D) 33.74

E) 63.96