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A is also incorrect for Part 1. But now I'm scared I'm misremembering the % values for standard deviations (but I just confirmed I'm not). What percentage of results in a normal distribution are covered by the following:
1 standard deviation
2 standard deviations
3 standard deviations
The fact that each question on the test is worth 2 points is irrelevant to the answers. All you need is the mean score and the standard deviation. You don't need to know how many points each question was worth or how many points were possible.
The answers would be the same if each question were worth one point and there were 16,000 questions on the test.
For part 2, the key point of the question is that a score of 50 points is five standard deviations (30 point difference = 6*5) away from the mean. What percentage of results will be five or more standard deviations from the mean in a normal distribution?
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