SPM 2018 Add Maths Paper 1, Question 1
Solved on video in English and Bahasa Melayu · 2 marks · 3:58 video
The question
Diagram 1 shows a probability distribution graph for a random variable X, X ~ N(mu, sigma². It is given that AB is the axis of symmetry of the graph. (a) State the value of mu. (b) If the area of the shaded region is 0.38, state the value of P(5 <= X <= 15).
[2 marks]
3:58Step 1
The mean of a normal distribution lies on its axis of symmetry. AB is given as the axis of symmetry and its foot A is at the mark 10 on the x-axis, so mu = 10.
5 more steps, each with the reason for it, in the full solution
Final answer
(a) μ = 10; (b) P(5 ≤ X ≤ 15) = 0.24
Where students lose marks
Watch out: the shading is the upper tail P(X ≥ 15), and 5 and 15 are symmetric about the mean 10.
Watch every step of this question solved on video (3:58), 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.
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