SPM 2017 Add Maths Paper 1, Question 24Probability Distribution

Solved on video in English and Bahasa Melayu · 3 marks · Form 5, Probability Distribution · 5:46 video

The question

Diagram 9 shows the graph of binomial distribution X ~ B(3, p). (a) Express P(X=0) + P(X>2) in terms of a and b. (b) Find the value of p.

[3 marks]

Step 1

Since X can only take values 0,1,2,3, the probabilities sum to 1: P(X=0)+P(X=1)+P(X=2)+P(X=3) = 1, i.e. P(X=0) + a + b + P(X=3) = 1.

Why this step

The bars cover every possible outcome, so their heights must add to 1. That's how we bring a and b into the equation.

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

Final answer

(a) 1 − a − b; (b) p = 4/7

Where students lose marks

Watch out: X can't exceed 3, so P(X>2) = P(X=3). In (b), the cube root gives 1 − p, so subtract from 1.

Watch every step of this question solved on video (5:46), with the reason behind each step and a box that checks your own answer.

No card. Every past-year question on video, in English and BM.