Answer:
d. -1.9; not unusual
Step-by-step explanation:
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;
.
So
A z-score of -1.9 is higher than -2 and lower than 2, so it is not unusual.
So the correct answer is:
d. -1.9; not unusual