In: Statistics and Probability
Given the following hypothesis test:
“It is believed that the mean amount of water per day that the
Gondorans drink is L liters. A random sample of 36 Gondorans is
observed. The average amount of water they drink per day is 1.62
liters, with a standard deviation of 0.4 liters. Is the mean amount
of water that Gondorans drink less than L liters? Test with α =
0.025.”
What is the biggest possible value of L (rounded to two digits
after the decimal point) so that the null hypothesis is still
retained?
L = ___________________
Ho : µ = 1.75
Ha : µ < 1.75
(Left tail test)
Level of Significance , α =
0.03
sample std dev , s = 0.4000
Sample Size , n = 36
Sample Mean, x̅ = 1.6200
degree of freedom= DF=n-1= 35
Standard Error , SE = s/√n = 0.4000 / √
36 = 0.0667
t-test statistic= (x̅ - µ )/SE = ( 1.620
- 1.75 ) / 0.0667
= -1.95
critical t value, t* =
-2.0301 [Excel formula =t.inv(α/no. of tails,df)
]
p-Value = 0.0296 [Excel formula
=t.dist(t-stat,df) ]
Decision: p-value>α, Do not reject null hypothesis
L = 1.75
THANKS
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