Answer:
We conclude that the population mean is equal to 490.
Step-by-step explanation:
We are given that a random sample of 15 observations is selected from a normal population. The sample mean was 495 and the sample standard deviation 9.
Let = <u><em>population mean</em></u>.
So, Null Hypothesis, : = 490 {means that the population mean is equal to 490}
Alternate Hypothesis, : 490 {means that the population mean is different from 490}
The test statistics that will be used here is <u>One-sample t-test statistics</u> because we don't know about population standard deviation;
T.S. = ~
where, = sample mean = 495
s = sample standard deviation = 9
n = sample of observations = 15
So, <em>the test statistics </em>=
~
= 2.152
The value of t-test statistics is 2.152.
Now, at a 0.01 level of significance, the t table gives a critical value of -2.977 and 2.977 at 14 degrees of freedom for the two-tailed test.
Since the value of our test statistics lies within the range of critical values of t, so <u><em>we have insufficient evidence to reject our null hypothesis</em></u> as the test statistics will not fall in the rejection region.
Therefore, we conclude that the population mean is equal to 490.