CIE iGCSE Maths C8.1 Introduction to probability Exam Style Practice Questions- Paper 1

Question

The diagram shows a fair 8-sided spinner.
The numbers on the spinner are 3, 4, 4, 7, 7, 7, 8 and 9.

(a) The spinner is spun once.
Write down the probability that the spinner lands on
(i) the number 7,
(ii) a number greater than 2.

(b) The spinner is spun 160 times.
Work out the expected number of times the spinner lands on the number 7.

▶️ Answer/Explanation

Answers:

(a)(i) \(\frac{3}{8}\)

(a)(ii) 1

(b) 60

Explanation:

(a)(i) Probability of landing on 7: There are 3 sevens out of 8 possible outcomes → \(\frac{3}{8}\).

(a)(ii) All numbers (3,4,7,8,9) are >2 → Probability = \(\frac{8}{8} = 1\).

(b) Expected number of 7’s in 160 spins: \(160 \times \frac{3}{8} = 60\).

Question

A 4-sided spinner is numbered 1, 2, 3 and 4.
The table shows the probability of the spinner landing on 1, 2 and 4.

Number	1	2	3	4
Probability	0.27	0.18		0.32

Complete the table.

▶️ Answer/Explanation

Solution

Ans: 0.23

Total probability must equal 1.

Sum of known probabilities: 0.27 + 0.18 + 0.32 = 0.77

Missing probability: 1 – 0.77 = 0.23

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