Question

You apply to 20 graduate programs, 10 of which are in clinical psychology, 5
of which are in counseling, and 5 of which are in social work. You receive a message
from your roommate that you got a letter back from a grad school, but she doesn’t say
which one. Calculate the probabilities that the letter is from:


a. a clinical program

b. a counseling program

c. anything but a social work program 

Answer 1

Clinical Program: 50%

Counseling Program: 25%

Anything but Social Work: 75%

Explanation:

Clinical Psychology: 10/20 50%

Counseling: 5/20 25%

Social Work: 5/20 25%

Answer 2

The first is 10/20, that is, 50%.
The second is 5/20, that is, 25%.
The third is 15/20, that is, 75%.
Take good cases divided by all cases.