Solution: 2014 Fall Final - 20
Author: Michiel SmidQuestion
Assume you answer the first question in this exam by choosing one of the four answers uniformly at random.
You answer the second question by choosing, again uniformly at random, one of the three answers you did not choose in
the first question. What is the probability that you answer the second question correctly?
(a)
$\frac{1}{3}$
(b)
$\frac{1}{4}$
(c)
None of the above.
(d)
$\frac{1}{4} \cdot \frac{1}{3} + \frac{3}{4} \cdot \frac{1}{4}$
Solution
I mean, there are a total of 4 options, and only one of them is right.
The probability of getting the right answer is $ \frac{1}{4} $.