Statistics and Probability

The first picture above is an additional info for the second picture below

(Note: First pic, serve as a basis for 2nd pic)

Vn Study the illustrative sample problems below. 1. Assume that the variable is normally distributed, the average time it takes a group of senior high school students to complete a certain examination is 46.2 minutes while the standard deviation is 8 minutes. What is the probability that a randomly selected senior high school students will complete the examination in less than 43 minutes? Does it seem reasonable that a senior high school student would finish the examination in less than 43 minutes? a.) If 50 randomly selected senior high school students take the examination, what is the probability that the mean time it takes the group to complete the test will be less than 43 minutes? Does it seem reasonable that the mean of the 50 senior high school students could be less than 43 minutes? 1. If 30 randomly selected junior high school students take the examination, what is the probability that the mean time it takes the group to complete the test will be less than 20 minutes? Does it seem reasonable that the mean of the 30 junior high school students could be less than 20 minutes? 2. If 19 selected Grade 6 students take the examination, what is the probability that the mean time it takes the group to complete the test will be less than 38 minutes? Does it seem reasonable that the mean of the 19 Grade 6 elementary students could be less than 38 minutes? 3. Assume that the variable is normally distributed, the average time it takes a group of junior high school students to complete a certain examination is 25 minutes while the standard deviation is 13 minutes. What is the probability that a randomly selected junior high school students will complete the examination in less than 40 minutes? Does it seem reasonable that a junior high school student would finish the examination in less than 40 minutes