Valentines Probability

Giving out valentines cards 20 times and choosing a red card 11 times. Find the probability of the event and the probability of its complement.

• P(red card) = 11/20

• P(not red card) = 9/20

It rained three days last week. Find the probability of the event and the probability of its complement.

• P(rain) = 3/7

• P(no rain) = 4/7

A box with 15 valentines, 7 are from your secret admirer. Find the probability of the event and the probability of its complement.

• P(from secret admirer) = 7/15

• P(not from secret admirer) = 8/15

Picking a red valentine from a bag of 6 valentines, only one of which is red. Find the probability of the event and the probability of its complement.

• P(red valentine) = 1/6

• P(not red valentine) = 5/6

You received valentines in 2 out of 7 classes. Find the probability of the event and the probability of its complement.

• P(received valentines) = 2/7

• P(did not receive valentines) = 5/7

Giving out valentines 35 times and choosing a specific friend 19 times. Find the probability of the event and the probability of its complement.

• P(specific friend) = 19/35

• P(other friends) = 16/35

Your box of ten valentines has one with a heart on it. Find the probability of the event and the probability of its complement.

• P(heart) = 1/10

• P(not heart) = 9/10

A box with 2 red, 3 green, and 5 blue valentines. Find the probability of the event and the probability of its complement.

• P(green) = 3/10

• P(not green) = 7/10

Choosing a red valentine from a bag of 6 valentines, 4 of which are red. Find the probability of the event and the probability of its complement.

• P(red) = 4/6 or 2/3

• P(not red) = 2/6 or 1/3

Choosing 11 valentines randomly and finding 7 with hearts and 4 without. Find the probability of choosing a valentine with a heart and the probability of its complement.

• P(hearts) = 7/11

• P(not hearts) = 4/11