Compound probability. Game on.

Compound probability is a grade 7 math skill aligned to Common Core standard 7.SP.C.8: find probabilities of compound events using organized lists, tables, tree diagrams, and simulation. Below are 8 practice questions with answers and step-by-step explanations, drawn from the 18 compound probability problems our math games drill.

CCSS 7.SP.C.818 questions in the bank
Kickoff

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Warm-upeasy

A meal has 3 mains and 4 sides. How many different (main, side) combinations are possible?

By the multiplication principle: 3×4=123 \times 4 = 12.

Mid-gameeasy

For two independent events, the probability of flipping two heads in a row: P(A)=12P(A)=\tfrac{1}{2}, P(B)=12P(B)=\tfrac{1}{2}. Find P(A and B)P(A \text{ and } B) as a simplified fraction.

Multiply: P(A and B)=12×12=14P(A \text{ and } B) = \tfrac{1}{2} \times \tfrac{1}{2} = \tfrac{1}{4}.

Mid-gameeasy

Two fair coins are flipped. How many outcomes are in the sample space?

Each coin has 22 outcomes, so the sample space has 2×2=42 \times 2 = 4 outcomes: HH, HT, TH, TT.

Mid-gameeasy

For two independent events, the probability of rolling two 6's: P(A)=16P(A)=\tfrac{1}{6}, P(B)=16P(B)=\tfrac{1}{6}. Find P(A and B)P(A \text{ and } B) as a simplified fraction.

Multiply: P(A and B)=16×16=136P(A \text{ and } B) = \tfrac{1}{6} \times \tfrac{1}{6} = \tfrac{1}{36}.

Mid-gameeasy

Mia can pick from 55 shirts and 22 hats. How many different (shirt, hat) outfits are possible?

By the counting principle: 5×2=105 \times 2 = 10.

Mid-gameeasy

For two independent events, the probability of a head then a 4: P(A)=12P(A)=\tfrac{1}{2}, P(B)=16P(B)=\tfrac{1}{6}. Find P(A and B)P(A \text{ and } B) as a simplified fraction.

Multiply: P(A and B)=12×16=112P(A \text{ and } B) = \tfrac{1}{2} \times \tfrac{1}{6} = \tfrac{1}{12}.

Mid-gameeasy

Two fair coins are tossed. What is the probability of getting exactly one head?

The sample space is HH, HT, TH, TT. Exactly one head appears in 22 of the 44 equally likely outcomes: 24=12\dfrac{2}{4} = \dfrac{1}{2}.

Buzzer beatereasy

For two independent events, the probability of an even roll then a head: P(A)=36P(A)=\tfrac{3}{6}, P(B)=12P(B)=\tfrac{1}{2}. Find P(A and B)P(A \text{ and } B) as a simplified fraction.

Multiply: P(A and B)=36×12=14P(A \text{ and } B) = \tfrac{3}{6} \times \tfrac{1}{2} = \tfrac{1}{4}.

Overtime

10 more. Played, not assigned.

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