An analysis of the grades on the first test in History 101revealed that they approximate a normal curve with a mean of 75 anda standard deviation of 8. The instructor wants to award the gradeof A to the upper 10 percent of the test grades. What is thedividing point between an A and a B grade? A) 80 B) 85 C) 90 D) 95Answer: B Please work this out for me step- by- step.