Twice a number is three more than nine
2 answers:
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Answer:
b. Kathy
Step-by-step explanation:
We compare each of their score by how far away from the mean when in term of the standard deviation. Using the following formula
For John he is (85 - 75)/5 = 2.
For Kathy she is (80 - 50)/10 = 3.
Since Kathy is 3 standard deviation better than her class' average, while John is only 2's. We conclude that Kathy did better.