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Sampling, Inference & the t-Test · Question 64 of 70

What is the t-value for the sample of 16 bulbs?

Question 64

MediumOriginal question

A bulb maker claims its bulbs last 1,000 hours on average. A sample of 16 bulbs lasts a mean of 960 hours with standard deviation 80 hours. At the 5% level, the two-tailed critical value of $t$ for 15 degrees of freedom is 2.131.

What is the $t$ -value for the sample of 16 bulbs?

-8

Correct answerYour answer

-3

Correct answerYour answer

-2

Correct answerYour answer

-0.5

Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer C

Correct answer: C

$t = \frac{960 - 1{,}000}{80/\sqrt{16}} = \frac{-40}{20}$ .
$t = -2$ .

Worth noting

$-0.5$ divides by $s = 80$ alone; the standard error is $\frac{80}{4} = 20$ .

Concept: Computing t
Typical timeTypical: 120 s
Your timeYours: —

The rule this testsThe one-sample t-test

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