SPM 2017 Add Maths Paper 1, Question 21Probability Distribution

Solved on video in English and Bahasa Melayu · 3 marks · Form 5, Probability Distribution · 5:59 video

The question

A biased cube dice is thrown. The probability of getting the number '4' is 1/16 and the probabilities of getting other than number '4' are equal to each other. If the dice is thrown twice, find the probability of getting two different numbers. Give your answer in the simplest fraction form.

[3 marks]

SPM 2017 Add Maths Paper 1, Question 21: the question as drawn in Eduly's video5:59

Step 1

Let x = P(1) = P(2) = P(3) = P(5) = P(6). Since all probabilities sum to 1: x+x+x+(1/16)+x+x = 1, so 5x = 1 - 1/16 = 15/16, giving x = 3/16.

Why this step

The six outcomes cover everything a throw can give, so their probabilities must total 1. That is what lets us solve for the unknown x.

3 more steps, each with the reason for it, in the full solution

Final answer

105/128

Where students lose marks

Watch out: 'same number' also includes two 4s. Add (1/16)² to 5x², then subtract from 1 carefully.

Watch every step of this question solved on video (5:59), with the reason behind each step and a box that checks your own answer.

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