A bottled water distributor wants to determine whether the mean amount of water contained inâ 1-gallon bottles purchased from a nationally known water bottling company is actually 1 gallon. You know from the water bottling company specifications that the standard deviation of the amount of water is 0.008 gallon. You select a random sample of 50 bottles, and the mean amount of water perâ 1-gallon bottle is 0.995 gallon.

Required:
a. Is there evidence that the mean amount is different from 1.0 gallon?
b. What is the test statistic?
c. Compute theâ p-value and interpret its meaning.
d. Construct a 95% confidence interval estimate of the population mean amount of water perâ 1-gallon bottle.

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ogorwyne ogorwyne · Answer 1 · 2021-04-09T21:48:38+02:00

Answer:

1. There is evidence that mean is different from 1.0 gallon

2. test statistic = -4.42

3. p value = 0.00001

4. 0.9928,0.9972

Step-by-step explanation:

h0: u = 1.0

h1: u not equal to 1.0

alpha = 0.05

sd = 0.008

n = 50

mean = 0.995

standard error se = 0.008/√50 = 0.00113

test statistics calculation

0.995-1/0.00113

= -0.005/0.00113

= -4.42

p value calculation

using the z test statistics and alpha = 0.05

the p value using a p value calculator = 0.00001

0.00001<0.05

so we Reject the null hypothesis

we conclude there is enough evidence that mean is different from 1.0

95% confidence interval

Z alpha/2 = 0.025

we find z value using excel function

NORMSINV (0.025)

|Z| = 1.96

Standard error se = 0.00113

margin of error E = 1.96 x 0.00113 = 0.0022148

confidence interval =

0.995 - 0.0022148, 0.995 + 0.0022148

= 0.9928, 0.9972