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Simple probability

Find the chance of drawing a named color from a bag.

Practice + answer key · 4 pages

Worksheet settings12 questions · 2 columns · A4
Counters per color

Choose positive counts for red, blue, and green counters.

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Simple probabilitySimple probability. Practice. A bag has 3 red, 7 blue, and 1 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)? A bag has 10 red, 9 blue, and 9 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)? A bag has 1 red, 3 blue, and 8 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)? A bag has 5 red, 8 blue, and 6 green counters. One counter is chosen at random, with each counter equally likely. What is P(blue)? A bag has 1 red, 4 blue, and 9 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)? A bag has 10 red, 9 blue, and 7 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)? A bag has 5 red, 4 blue, and 2 green counters. One counter is chosen at random, with each counter equally likely. What is P(red)? A bag has 8 red, 8 blue, and 8 green counters. One counter is chosen at random, with each counter equally likely. What is P(red)?Name __________________________Date _______________Simple probabilityGive each probability as a simplified fraction.Worked exampleA bag contains 3 red, 2 blue, and 5 green counters. What is P(red)? → 3/10Total counters = 3 + 2 + 5 = 10.1.A bag has 3 red, 7 blue, and 1green counters. One counter ischosen at random, with eachcounter equally likely. What isP(green)?2.A bag has 10 red, 9 blue, and 9green counters. One counter ischosen at random, with eachcounter equally likely. What isP(green)?3.A bag has 1 red, 3 blue, and 8green counters. One counter ischosen at random, with eachcounter equally likely. What isP(green)?4.A bag has 5 red, 8 blue, and 6green counters. One counter ischosen at random, with eachcounter equally likely. What isP(blue)?5.A bag has 1 red, 4 blue, and 9green counters. One counter ischosen at random, with eachcounter equally likely. What isP(green)?6.A bag has 10 red, 9 blue, and 7green counters. One counter ischosen at random, with eachcounter equally likely. What isP(green)?7.A bag has 5 red, 4 blue, and 2green counters. One counter ischosen at random, with eachcounter equally likely. What isP(red)?8.A bag has 8 red, 8 blue, and 8green counters. One counter ischosen at random, with eachcounter equally likely. What isP(red)?MathSprig · mathsprig.site · support@mathsprig.sitePage 1 of 2mathsprig-1 · mathsprig-v1 · 8e9fbdf4
Simple probabilitySimple probability. Practice. A bag has 10 red, 8 blue, and 6 green counters. One counter is chosen at random, with each counter equally likely. What is P(red)? A bag has 9 red, 5 blue, and 3 green counters. One counter is chosen at random, with each counter equally likely. What is P(red)? A bag has 5 red, 9 blue, and 2 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)? A bag has 4 red, 9 blue, and 5 green counters. One counter is chosen at random, with each counter equally likely. What is P(red)?Name __________________________Date _______________Simple probabilityGive each probability as a simplified fraction.9.A bag has 10 red, 8 blue, and 6green counters. One counter ischosen at random, with eachcounter equally likely. What isP(red)?10.A bag has 9 red, 5 blue, and 3green counters. One counter ischosen at random, with eachcounter equally likely. What isP(red)?11.A bag has 5 red, 9 blue, and 2green counters. One counter ischosen at random, with eachcounter equally likely. What isP(green)?12.A bag has 4 red, 9 blue, and 5green counters. One counter ischosen at random, with eachcounter equally likely. What isP(red)?MathSprig · mathsprig.site · support@mathsprig.sitePage 2 of 2mathsprig-1 · mathsprig-v1 · 8e9fbdf4
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Practice + answer key · 4 pages

Measurement & data

What you’ll practice

Find the probability of drawing one named color and simplify the answer.

Count the counters of the color you want, then count all the counters in the bag. Write the first count over the total and simplify the fraction.

How this skill works

Add all color counts to find the total number of objects.

Put the requested color count over that total, then simplify. The result must lie from 0 to 1.

Worked example

A bag contains 3 red, 2 blue, and 5 green counters. What is P(red)?
  1. Total counters = 3 + 2 + 5 = 10.
  2. There are 3 favorable red counters.
  3. P(red) = 3/10.

Answer: 3/10

Teaching notes

  • Use the total of every color in the denominator.
Practice questions
  1. A bag has 3 red, 7 blue, and 1 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)?
  2. A bag has 10 red, 9 blue, and 9 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)?
  3. A bag has 1 red, 3 blue, and 8 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)?
  4. A bag has 5 red, 8 blue, and 6 green counters. One counter is chosen at random, with each counter equally likely. What is P(blue)?
  5. A bag has 1 red, 4 blue, and 9 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)?
  6. A bag has 10 red, 9 blue, and 7 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)?
  7. A bag has 5 red, 4 blue, and 2 green counters. One counter is chosen at random, with each counter equally likely. What is P(red)?
  8. A bag has 8 red, 8 blue, and 8 green counters. One counter is chosen at random, with each counter equally likely. What is P(red)?
  9. A bag has 10 red, 8 blue, and 6 green counters. One counter is chosen at random, with each counter equally likely. What is P(red)?
  10. A bag has 9 red, 5 blue, and 3 green counters. One counter is chosen at random, with each counter equally likely. What is P(red)?
  11. A bag has 5 red, 9 blue, and 2 green counters. One counter is chosen at random, with each counter equally likely. What is P(green)?
  12. A bag has 4 red, 9 blue, and 5 green counters. One counter is chosen at random, with each counter equally likely. What is P(red)?
Answers and steps
  1. 1/11
    1. Total = 3 + 7 + 1 = 11.
    2. Favorable counters = 1. Probability = 1/11 = 1/11.
  2. 9/28
    1. Total = 10 + 9 + 9 = 28.
    2. Favorable counters = 9. Probability = 9/28 = 9/28.
  3. 2/3
    1. Total = 1 + 3 + 8 = 12.
    2. Favorable counters = 8. Probability = 8/12 = 2/3.
  4. 8/19
    1. Total = 5 + 8 + 6 = 19.
    2. Favorable counters = 8. Probability = 8/19 = 8/19.
  5. 9/14
    1. Total = 1 + 4 + 9 = 14.
    2. Favorable counters = 9. Probability = 9/14 = 9/14.
  6. 7/26
    1. Total = 10 + 9 + 7 = 26.
    2. Favorable counters = 7. Probability = 7/26 = 7/26.
  7. 5/11
    1. Total = 5 + 4 + 2 = 11.
    2. Favorable counters = 5. Probability = 5/11 = 5/11.
  8. 1/3
    1. Total = 8 + 8 + 8 = 24.
    2. Favorable counters = 8. Probability = 8/24 = 1/3.
  9. 5/12
    1. Total = 10 + 8 + 6 = 24.
    2. Favorable counters = 10. Probability = 10/24 = 5/12.
  10. 9/17
    1. Total = 9 + 5 + 3 = 17.
    2. Favorable counters = 9. Probability = 9/17 = 9/17.
  11. 1/8
    1. Total = 5 + 9 + 2 = 16.
    2. Favorable counters = 2. Probability = 2/16 = 1/8.
  12. 2/9
    1. Total = 4 + 9 + 5 = 18.
    2. Favorable counters = 4. Probability = 4/18 = 2/9.