CA Foundation P3 · Chapter 16 · Question 9 of 9
Marks of 2,000 students are normally distributed with mean 50 and SD 5. Given areas from z = 0: 0.3413 for z = 1 and 0.4772 for z = 2, the number of students scoring between 45 and 60 is about:
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Reveal answer & explanation
Correct answer: C) 1637
Explanation
z for 45 = (45 − 50)/5 = −1 and z for 60 = (60 − 50)/5 = 2. Area = 0.3413 + 0.4772 = 0.8185. Number = 0.8185 x 2,000 = 1,637. Using ±1 (0.6826) gives 1,365, and 0.4772 alone gives 954.
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