Answer:
a)
b)
c) Mary's score was 241.25.
Step-by-step explanation:
Problems of normally distributed samples can be solved using the z-score formula.
In a set with mean and standard deviation
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:
a) Find the z-score of John who scored 190
b) Find the z-score of Bill who scored 270
c) If Mary had a score of 1.25, what was Mary’s score?
Mary's score was 241.25.