The water works commission needs to know the mean household usage of water by the residents of a small town in gallons per day. they would like the estimate to have a maximum error of 0.15 gallons. a previous study found that for an average family the standard deviation is 2.3 gallons and the mean is 17.6 gallons per day. if they are using a 80% level of confidence, how large of a sample is required to estimate the mean usage of water? round your answer up to the next integer.

387

Step-by-step explanation:

Given : Standard deviation:

Margin of error : 0.15

Critical value for 80% confidence interval = 1.2816

Required minimum sample size :

Hence, the minimum sample size required to estimate the mean usage of water = 387

solution:

→c= a b , that is product of a and b is possible only when when a is m × n matrix and b is n × p matrix.

that is, number of columns of a= number of rows of b.

so, size of matrix , c= a b is , if a = (m × n)matrix

b= (n × p)matrix

then a b = [ (m × n)matrix] ×[   (n × p)matrix ]

→→c= a b= [m × p ] matrix

→→size of product a b will be equal to = number of rows of a × number of columns of b

step-by-step explanation: 2