Answer:
a) 8.23% probability that a piece of pottery will be finished within 95 minutes
b) 0.28% probability that it will take longer than 110 minutes.
Step-by-step explanation:
Normal distribution:
When the distribution is normal, we use 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.
Two variables:
Means
Standard deviations
Sum:
In this question:
So
A) What is the probability that a piece of pottery will befinished within 95 minutes?
This is the pvalue of Z when X = 95.
has a pvalue of 0.0823
8.23% probability that a piece of pottery will befinished within 95 minutes.
B) What is the probability that it will take longer than 110 minutes?
This is 1 subtracted by the pvalue of Z when X = 110.
has a pvalue of 0.9972
1 - 0.9972 = 0.0028
0.28% probability that it will take longer than 110 minutes.