The average person uses 123 gallons of water daily. If the standard deviation is 21 gallons,...

The average person uses 123 gallons of water daily. If the standard deviation is 21 gallons, find the probability that the mean usage of water of a randomly selected sample of 15 people will be greater than 126 gallons. Assume that the variable is normally distributed

Solutions

Expert Solution

Solution :

Given that,

mean = = 123

standard deviation = = 21

n=15

= =123

= / n = 21/ 15 = 5.42

P( > 126) = 1 - P( <126 )

= 1 - P[( - ) / < (126-123) /5.42 ]

= 1 - P(z <0.55 )

Using z table

= 1 - 0.7088

probability= 0.2912

orchestra answered 1 year ago

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