Question

At a certain college, 85% of the students use Facebook, 20% use Twitter, and 35% use Instagram. A

small portion of 5% of students do not use neither Facebook nor Twitter.

a) What is the probability that a randomly chosen student at the college uses both Facebook and

Twitter?

b) What is the probability that a randomly chosen student at the college uses Facebook but not Twitter?

c) Show that in general, for any two events E and F in a sample space Ω,

P(E∩F) ≥ P(E) + P(F) − 1

.

Answer 1