SPM 2017 Add Maths Paper 2, Question 7Probability Distribution
Solved on video in English and Bahasa Melayu · 10 marks · Form 5, Probability Distribution · 8:36 video
The question
(a) The mass of honeydews produced in a plantation is normally distributed with a mean of 0.8 kg and a standard deviation of 0.25 kg. The honeydews are being classified into three grades A, B and C according to their masses: Grade A > Grade B > Grade C. (i) The minimum mass of a grade A honeydew is 1.2 kg. If a honeydew is picked at random from the plantation, find the probability that the honeydew is of grade A. (ii) Find the minimum mass, in kg, of grade B honeydew if 20% of the honeydews are of grade C. (b) At the Shoot the Duck game booth at an amusement park, the probability of winning is 25%. Jason bought tickets to play n games. The probability for Jason to win once is 10 times the probability of losing all games. (i) Find the value of n. (ii) Calculate the standard deviation of the number of wins.
[10 marks]
8:36Step 1
Let X be the mass, X ~ N(0.8, 0.25². P(grade A) = P(X > 1.2) = P(Z > (1.2-0.8)/0.25) = P(Z > 1.6) = 0.0548
7 more steps, each with the reason for it, in the full solution
Final answer
(a)(i) 0.0548; (ii) 0.5895 kg; (b)(i) n = 30; (ii) 2.372
Where students lose marks
Watch out: a point below the mean has a negative z-value. In (b), take C(n,1) = n and cancel the powers of 0.75 carefully.
Watch every step of this question solved on video (8:36), 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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