Dullco Manufacturing claims that its alkaline batteries last

Dullco Manufacturing claims that its alkaline batteries last at least 40 hours on average in a certain type of portable CD player. But tests on a random sample of 18 batteries from a days large production run showed a mean battery life of 37.8 hours with a standard deviation of 5.4 hours. To test DullCo?s hypothesis, the p-value is: slightly less than .05. exactly equal to .05. slightly greater than .05. uncertain without knowing a.

Solution

Answer to the question)

Ho: M = 40

Ha: M < 40

[left tailed test]

.

t = (x bar - M) / (s/sqrt(n))

t = (37.8 -40) / (5.4/sqrt(18))

t = -1.72848

df = 18-1 = 17

.

The P value = 0.05101

.

tis P value is \"Slightly Greater than 0.05\"

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