Answer:
A.0.4477
Step-by-step explanation:
Problems of normally distributed samples are 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:
What is the probability that a randomly selected exam will require between 14 and 19 minutes to grade?
This probability is the pvalue of Z when X = 19 subtracted by the pvalue of Z when X = 14. So
X = 19
has a pvalue of 0.7389.
X = 14
has a pvalue of 0.2912
0.7389 - 0.2912 = 0.4477
So the correct answer is:
A.0.4477