Sara is taking a test made up of multiple choice and open ended questions. The multiple choice questions have a value of 4 point
1 answer:
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Here is dependence between scores and x-values:
where is the mean,
is standard deviation and i changes from 1 to 2.
1. When i=1, then
2. When i=2, then
Now solve the system of equations:
Subtract first equation from the second:
Then
Answer: the mean is 62, the standard deviation is 20.