Question

Suppose you randomly select a letter from BURGER AND STARBIRD. Imagine writing these letters on Ping-Pong balls – one letter per ball – then putting them all in a barrel and removing one. What is the probability of pulling out an R? What is the probability of pulling out a B? What is the probability of pulling out a letter that appears in the first half of the alphabet? What is the probability of pulling a vowel?

Answer 1

First, count the total number of letters in BURGER AND STARBIRD.
There are 17 letters.
Now count each type of letter you are interested in and divide by 17.

a) There are four R's, so the probability of pulling out an R is 4/17.

b) There are two B's, so the probability of pulling out an B is 2/17.

c) Letters A through M appear in the first half of the alphabet.
These letters are from the first half of the alphabet:
BGEADABID
There are 9 of them.
The probability of pulling out a letter that appears in the first half of the alphabet is 9/17.

d) These letters are vowels
UEAAI
There are five vowels.
The probability of pulling out a vowel is 5/17.