You just need to have an understanding of standardised scores (aka zscores) and the 65 - 95 - 97.5% rule.
A standardised score of 1 means that your score is equal to 1 standard deviation
above the mean.
(above average)A standardised score of 0 means your score is
equal to the mean.
(average)A standardised score of -1 means that your score is equal to 1 standard deviation
below the mean.
(below average)With that knowledge you can therefore apply your knowledge of the 65 - 95 - 97.5% rule which determines where most of the data (if it fits a bell shaped curve) should sit.
Solutions, below. Attempt it by yourself first though. Hopefully I'm correct with what's below (ran out of time to explain the rest.):
Spoiler
Cassie’s score in Further Maths is close to the average score for that subject. True, her standardised score is 0.1 and therefore every so slightly above the mean.
Cassie’s score in English placed her in the top 2.5% of students sitting the test. True, only 5% of the scores will sit above and below 2 standard deviations above and below the mean, 2.5% being above 2 standard deviations. And as her score for english is 2 standard deviations above, she fits within the top 2.5%.
Cassie’s score in Psychology placed her in the bottom 16% of students sitting the test. True
Cassie scored above average in all subjects. False. You can see that some of her standardised scores are below 0, which mean's that she was below the average.
More than half the class had a higher mark in Biology than Cassie. True
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