To determine the average water use, 109 people must be sampled.
1.9 gallons is the standard deviation.
E = 0.15 gallons maximum error
1.9 gallons on average
90% is the critical value.
1.645 is the 90% confidence interval.
sample size requirement,
n = (((z ÷ 2) × σ) ÷ E)²
n = (((1.645 ÷ 2) × 1.9) ÷ 0.15)²
n = ((0.8225 × 1.9) ÷ 0.15)²
n = (1.5627 ÷ 0.15)²
n = (10.418)²
n = 108.53 ≈ 109
As a result, the minimal sample size necessary to determine the mean water use = 109.
It is determined by dividing the average standard error by the squared of the sample size, and it decreases with increasing sample size. In other words, when the sample size is sufficiently big, the population mean approaches the population mean.
To learn more about the sample interval at
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Slope:2
y intercept: 5
so if your test has like a graph the dot will be at y=5
The answer to your question is $1978
301.6=3.14×4×h/3
301.6=12.56×h/3
3770/157=h/3
72 6/157=h. Hope it help!
