KS3Solutions

Probability

Answers grouped by subtopic.

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Different outcomes

  1. P-Q1
    Answer
    A coin is tossed. How many different outcomes are there?
    Working
    1. A coin has two outcomes: heads or tails, so there are 2 outcomes.
    Answer: 2
  2. P-Q6
    Answer
    Two coins are tossed. How many different outcomes are there?
    Working
    1. List outcomes: HH, HT, TH, TT.
    2. There are 4 outcomes.
    Answer: 4

Theoretical probability

  1. P-Q2
    Answer
    A fair die is rolled. Find the probability of getting a 6.
    Working
    1. There are 6 equally likely outcomes on a die.
    2. Only one outcome is a 6, so the probability is 16.
    Answer: 16
  2. P-Q3
    Answer
    A bag has 3 red and 1 blue counter. Find the probability of red.
    Working
    1. Total counters = 3 + 1 = 4.
    2. Red counters = 3.
    3. Probability = 34.
    Answer: 34
  3. P-Q4
    Answer
    A spinner has 4 equal sections: 1 green and 3 yellow. Find the probability of not landing on green.
    Working
    1. Not green sections = 3.
    2. Probability = 34.
    Answer: 34

Experimental probability

  1. P-Q5
    Answer
    A spinner lands on red 8 times out of 20 spins. Estimate the probability of red.
    Working
    1. Probability = number of red outcomestotal spins = 820 = 25.
    Answer: 25

Venn diagrams

  1. P-Q7
    Answer
    In a class of 20 students, 12 like football, 9 like basketball, and 5 like both. How many like neither?
    Working
    1. Like football or basketball = 12 + 9 - 5 = 16.
    2. Neither = 20 - 16 = 4.
    Answer: 4
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