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25 May 2019, 22:31
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A
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60% (01:32) correct
40%
(01:37)
wrong
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Justin took a test of French at school and scored 72 marks out of 100. If there were 20 students who appeared for the test, within how many standard deviations from the mean did Justin’s score lie?
(1) Darren and Matthew scored 70 and 75 respectively and their scores were within one standard deviation from the mean.
(2) The mean score of 20 students was 65 and Andrew who scored 59 was within one standard deviation of the mean.
(1) Darren and Matthew scored 70 and 75 respectively and their scores were within one standard deviation from the mean.
(2) The mean score of 20 students was 65 and Andrew who scored 59 was within one standard deviation of the mean.
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25 May 2019, 23:17
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Gmatprep998
I got it incorrect but realized my mistake, posting solution here:-
Statement 1.
Let x be mean, there can be three cases
1. 70<x<75
2. x<70,75
3. x>70,75. In all the three cases Justin's score falls within 1 SD bracket. Sufficient.
Statement 2.
65 is mean and 59 is within 1 SD bracket, so SD is surely SD>=6,
If SD is 6 Justin's score is in SD bracket 2 (Basically SD 2)
If SD is 7/8/9 etc. then Justin's score is within 1 SD. Insufficient.
Only A
10 Jul 2020, 18:26
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