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ProbabilityStatistics and probabilityMiddle schoolabout 0:39

An event has 5 favorable outcomes out of 20 equally likely outcomes. What is its probability?: animated lesson

A narrated, step-by-step probability video lesson with captions. Final answer: P(A) = 1/4 ≈ 0.25 (25%).

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Video with a synthetic English voice and captions. Pick another language for subtitles in that language, or open the interactive version.

Video narrated by a synthetic voice (Piper TTS, en_US-ljspeech-high voice (LJ Speech dataset, public domain)); the steps come from our maths engine and the answer was checked independently. Download MP4 (0.3 MB) · Captions (WebVTT)

Steps on screen

1. The problem
Worked example
An event has 5 favorable outcomes out of 20 equally likely outcomes. What is its probability?
2. Step by step
1. $P(A) = \frac{5}{20} = \frac{1}{4} \approx 0.25$
  Divide favorable outcomes by total equally likely outcomes
2. $P(A') = 1 - P(A) = \frac{3}{4} \approx 0.75$
  Complement: the event does not happen
3. $5 : 15$
  Odds in favor
3. The answer
$P(A) = \frac{1}{4} \approx 0.25$
P(A) = 1/4 ≈ 0.25 (25%)

Transcript

The problem. Here is the problem: An event has 5 favorable outcomes out of 20 equally likely outcomes. What is its probability? Single event (favorable divided by total).

Step by step. Divide favorable outcomes by total equally likely outcomes. Complement: the event does not happen. Odds in favor.

The answer. So the answer is P(A) equals 1 over 4 approximately 0.25 (25 percent). The event occurs in 5 of 20 equally likely outcomes, so its probability is 25 percent; it fails with probability 75 percent.

About probability

Probability of single events, complements, independent events and binomial outcomes.

An event has 5 favorable outcomes out of 20 equally likely…