Answer:
0.5793 = 57.93% probability that the household uses 480 gallons of water or less per month
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.
Mean of 470 gallons and standard deviation of 50 gallons.
This means that
What is the probability that the household uses 480 gallons of water or less per month?
This is the pvalue of Z when X = 480. So
has a pvalue of 0.5793
0.5793 = 57.93% probability that the household uses 480 gallons of water or less per month