The marks in a class test are normally distributed. The mean is 100 and the standard deviation is 10.
- Jason's mark is 115. What is his `z`-score? (1 mark)
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- Mary has a `z`-score of 0. What mark did she achieve in the test? (1 mark)
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- What percentage of marks lie between 80 and 110?
You may assume the following:
• 68% of marks have a `z`-score between –1 and 1
• 95% of marks have a `z`-score between –2 and 2
• 99.7% of marks have a `z`-score between –3 and 3. (2 marks)
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