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Answer:


Since the calculated values is lower than the critical value we have enough evidence to reject the null hypothesis at the significance level of 2.5% and we can say that the true mean is lower than 36 years old
Step-by-step explanation:
Data given
represent the sample mean
represent the sample standard deviation
sample size
represent the value that we want to test
represent the significance level for the hypothesis test.
t would represent the statistic (variable of interest)
represent the p value for the test (variable of interest)
System of hypothesis
We need to conduct a hypothesis in order to check if the true mean is less than 36 years old, the system of hypothesis would be:
Null hypothesis:
Alternative hypothesis:
The statistic is given by:
(1)
And replacing we got:
Now we can calculate the critical value but first we need to find the degreed of freedom:

So we need to find a critical value in the t distribution with df =21 who accumulates 0.025 of the area in the left and we got:

Since the calculated values is lower than the critical value we have enough evidence to reject the null hypothesis at the significance level of 2.5% and we can say that the true mean is lower than 36 years old
To factor both numerator and denominator in this rational expression we are going to substitute

with

; so

and

. This way we can rewrite the expression as follows:

Now we have two much easier to factor expressions of the form

. For the numerator we need to find two numbers whose product is

(30) and its sum

(-11); those numbers are -5 and -6.

and

.
Similarly, for the denominator those numbers are -2 and -5.

and

. Now we can factor both numerator and denominator:

Notice that we have

in both numerator and denominator, so we can cancel those out:

But remember than

, so lets replace that to get back to our original variable:

Last but not least, the denominator of rational expression can't be zero, so the only restriction in the variable is


Man why you asking us like we know