need some help please

QUESTION 1 A class has 80 students. Test 2 had a class average of 78 and a variance of 49. Answer the following 7 questions by finding the closest matches). (Assume Normal distribution). Assume a 90-80-70-60 = A-B-C-D scale. 1. What is the probability of getting an A? 2. How many will get an A? 3. What is the probability of getting a B? 4. What is the probability of getting a C? 5. How many people will fail the class? 6. If the bottom 5% will get an F, what will be the cut-off score? 7. If the top 15% get an A, what is the cutoff score for an A?QUESTION 5 Pioneer company has given an aptitude test to 71 potential job applicants. The test score had an average of 81 and a standard deviation of 8. Aptitude tests are known to follow a t-distribution. Pioneer rejects the bottom 5% of the applicants right away. The top 5% are hired immediately at managerial positions. Answer the next 6 questions. a. What is the degrees of freedom for this distribution? b. What is the tscore for someone who has scored 93? c. What is the cutoff score for those who'll be hired as managers? d. What will be the cutoff score fro those who'll get rejected right away? e. If we want to define the middle ofthe class (80%) to be average, what will be the lower cut-off scores? f' Ifwe want to define the middle of the class (80%) to be average, what will be the upper cut-off scores? QUESTION 6 Suppose a tire manufacturer wants to set a mileage guarantee on its new X3 70 tire. Tests revealed that the tire's mileage is normally distributed with a mean of 47,900 miles and a standard deviation of 2,050 miles, The manufacturer wants to set the guaranteed mileage so that no more than 5 percent of the tires will have to be replaced. What guaranteed mileage should the manufacturer announce? QUESTION 16 Z is a standard normal variable. Find the value of Z in the following. 1. The area between 0 and z is 0.4678. 2 The area to the right ofz is 0.1112. 3 The area to the left ofz is 0.8554 4. The area between -2 and z is 0.754. 5 The area to the left of z is 0.0681. 6 The area to the right of z is 0.9803. QUESTION 17 There are 90 people in the restaurant. The probability of someone ordering a drink with the food is 60%. Use Normal approximation of Binomial Distribution to answer the following 6 questions. 1' What is the mean of the Normal distribution? 2' What is the standard deviation of the normal distribution? 3' What is the probability that exactly 50 people will order a drink? 4. What the probability that more than 50 people will order a drink? 5. What is the probability that less than 50 people will order a drink? 6. What is the probability that between 52 or more and 55 or less people will order a drink