Estimating Probability from Data
Aligned to 7.SP.C.6 — Common Core State Standards for Mathematics.
What this lesson teaches
The experimental probability of an event is the fraction of times it happens: (number of times it occurs) ÷ (total trials). As the number of trials grows, this long-run relative frequency gets close to the true probability.
Worked example
A spinner lands on red 18 times in 60 spins. Experimental probability of red = 18 ÷ 60 = 0.3, or 30%.
Practice questions
- A coin lands heads 27 times in 50 flips. Find the experimental probability of heads.
- A bag draw gives blue 45 times in 150 tries. Estimate P(blue) as a fraction and a percent.
- Why does flipping a coin 500 times estimate P(heads) better than flipping it only 10 times?
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Estimar la Probabilidad a partir de Datos
La probabilidad experimental de un evento es la fracción de veces que ocurre: (número de veces que ocurre) ÷ (total de intentos). Al aumentar los intentos, esta frecuencia relativa a largo plazo se acerca a la probabilidad verdadera.
Ejemplo: Una ruleta cae en rojo 18 veces en 60 giros. Probabilidad experimental de rojo = 18 ÷ 60 = 0.3, o sea 30%.
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