Calculating Probability of Rolling Even

Pre-Algebra · Axiom Academy

EXAMPLE Calculating Probability of Rolling Even Find a probability by counting favorable outcomes over total outcomes, then write it as a fraction, decimal, and percent. You roll one fair standard die. What is the probability of rolling an even number? Give the answer as a fraction in lowest terms, as a decimal, and as a percent. Nice work — you found a probability from scratch and wrote it three different ways. Here is the recipe you used: Identify the favorable outcomes: the results that satisfy the event — here the even faces 2, 4, 6 . Count the total outcomes: a standard die has 6 equally likely faces. Simplify: reduce to lowest terms, . Decimal: divide top by bottom, . Percent: multiply the decimal by 100 , . A probability of (that is, ) means rolling even is exactly as likely as not — which makes sense, since half of the six faces are even.

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