ACT scores for the 1,171,460 members of the 2004 high school graduating class who took the test closely followed the Normal distribution with mean 20.9 and standard deviation 4.8. Choose two
students independently and at random from this group
A) What is the expected sum of their scores?
B) What is the expected difference of their scores?
C) What is the standard deviation of the difference in their scores?
Assuming the scores are independent
Round to 4 places after the decimal
Find the probability that the sum of their scores is greater than 50.
Round to 4 places after the decimal