Answer:
C
Step-by-step explanation:
Therefore, the correct answer is choice C. Hope this helps!
The Simmons family and the Wright family each used their sprinklers last summer. The water output rate for the Simmons family's
sprinkler was 20l per hour. The water output rate for the Wright family's sprinkler was 35l per hour. The families used their sprinklers for a combined total of 55 hours, resulting in a total water output 1475l of . How long was each sprinkler used?
2 answers:
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Answer:
The standard deviation of number of hours worked per week for these workers is 3.91.
Step-by-step explanation:
Problems of normally distributed samples can be solved using the z-score formula.
In a set with mean and standard deviation
, the zscore of a measure X is given by
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. Subtracting 1 by the pvalue, we This p-value is the probability that the value of the measure is greater than X.
In this problem we have that:
The average number of hours worked per week is 43.4, so .
Suppose 12% of these workers work more than 48 hours. Based on this percentage, what is the standard deviation of number of hours worked per week for these workers.
This means that the Z score of has a pvalue of 0.88. This is Z between 1.17 and 1.18. So we use
.
The standard deviation of number of hours worked per week for these workers is 3.91.