In a certain school, 200 students were surveyed regarding the number of hours they spend on Facebook daily. The results are as follows:

Question

NUMBER OF HOURS (X) ----- NUMBER OF STUDENTS

0 30

1 45

2 70

3 55

a.) Construct the probability distribution from the given table.

b.) Find the probability that a student chosen at random spends at least 2 hours on Facebook daily.

c. )Find the probability that a student chosen at random spends at most 1 hour on Facebook daily.

d.) Find the mean number of hours spent on Facebook daily.

Answer 1

a) This is a negatively skewed distribution.

b) P(X ≥ 2) = P(X = 2) + P(X = 3) = (70/200) + (55/200) = 0.35 + 0.28 = 0.63

c) P(X ≤ 1) = P(X = 0) + P(X = 1) = (30/200) + (45/200) = 0.15 + 0.23 = 0.38

d) x-bar: μ = [30(0) + 45(1) + 70(2) + 55(3)]/200 = 350/200 = 1.75 hours