tính trung bình và độ lệch tiêu chuẩn về thời gian chơi game online trung bình trong một tuần (xác suất thống kê toán kỹ thuật )

125 tickets were sold for the jazz band concert for a total of $1,022. students tickets cost $6 each, and general admission tickets cost $10 each. how many of each kind of tickets were sold?

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.1. (round your answers to four decimal places.) (a) if the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51?

Liz is shipping a package to her friend.the maximum weight of a medium flat-rate box is 20 pounds,including the box which weighs 6 ounces.write and solve an inequality to describe the possible weight ,w, of the contents that liz will ship to her friend if she must use a medium flat-rate box.