For numbers 5 -B, refer to the problem below. A population of 17-year old Senior High School students has a mean grade of 89 In Statistics and Probability with a standard deviation of 5. Assume that the wardable Is normally distributed 5. If 20 randomly selected students are taken, what is the probability that their mean grade will be less than 87? a. 0.0267 b. 0.0367 C. 0.0467 d. 0.0567 6. If 50 students were randomly selected, what percentage that their mean grade will exceed 90? a. 7.93% b. 6.93% c. 5.93% d. 4.93% 7. What is the probability of the students to have an average grade between 88 and 917 a. 0.0793 b. 0.1554 C. 0.0761 d. 0.2347 B. Which of following is the correct standard normal curve for number 5 question? b. 20-1.79 20-1.79 C. d. 2 -1.79 2 = 1.79 9. Which of the following used z score formula for infinite population? a. z=Ju b. Z = N-K c. both d. none of these