The mean is the same thing as the average of the sales. So the first six months sales were 52, 82, 71, 92, 51, and 28. the average of these six numbers is 62.66667 which is short of the 65 mean.
52+82+71+92+51+28=376
take that number 376 and divide by the number of months (6)
Ok if half are female that means 40 than 80 more for each of them because they all produce 80 so 80 times 40 = 3200 your gonna do the same 2 more times because of 3 generations so 3200 times 3 = 9600 in total