Jimmy spent 45 minutes to finish his homework. There are 20 problems. What is the average amount of time he spends to finish eac
1 answer:
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Answer:
Exactly 16%.
Step-by-step explanation:
Normal Probability Distribution
Problems of normal distributions can be solved using the z-score formula.
In a set with mean and standard deviation
, the z-score 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 p-value, we get the probability that the value of the measure is greater than X.
The mean of a certain set of measurements is 27 with a standard deviation of 14.
This means that
The proportion of measurements that is less than 13 is
This is the p-value of Z when X = 13, so:
has a p-value of 0.16, and thus, the probability is: Exactly 16%.