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Answer:
The percentle for Abby's score was the 89.62nd percentile.
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean and standard deviation(which is the square root of the variance)
, 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.
Abby's mom score:
93rd percentile in the math SAT exam. In 1982 the mean score was 503 and the variance of the scores was 9604.
93rd percentile. X when Z has a pvalue of 0.93. So X when Z = 1.476.
So
Abby's score
She scored 648.
So
has a pvalue of 0.8962.
The percentle for Abby's score was the 89.62nd percentile.