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Da VIP Academy / GED / Math / Data, Statistics & Probability

Probability & Counting

Find simple and compound probabilities and count outcomes.

Practice this skillAll Math skills

How it works

Favorable over total

A bag with 4 red and 6 blue marbles gives P(red) = 4/10 = 2/5. Probabilities always land between 0 and 1.

Independent events multiply

Two coin flips both landing heads: ½ × ½ = ¼. If the first item is not replaced, the second denominator shrinks by one.

Worked examples

  1. A bag holds 4 red and 6 blue marbles. What is P(red)?

    1. Total = 10.
    2. Favorable = 4.
    3. 4/10 = 2/5.

Words to know

Independent events
Events where one result does not affect the other.

Test-day tips

  • • "And" usually means multiply; "or" usually means add.
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