Question

The probability of drawing a quarter from a bag of coins is 4/5. What is the probability of drawing a coin that is not a quarter from the bag?
A. 20% B. 40% C. 75% D. 90%

Answer 1

The sum of probability for an event happening and not happening must be equal to 1 because there is a 100% chance that one or the other will occur.

So the probability on not drawing a quarter:

P(!Q)=1-4/5

P(!Q)=5/5-4/5

P(!Q)=1/5

As a percentage:

p/100=1/5

p=100/5

p=20%