Answer: Option 'd' is correct.
Step-by-step explanation:
Since we have given that
Margin of error = 0.5 years
Standard deviation = 5
At 90% confidence, z = 1.645
We need to find the minimum size of the sample they must take.
So,
Hence, Option 'd' is correct.
Answer:
We know that the p value is 0.1, and since is a left tailed test would be given by:
And we can find the calculated value using excel or the t table.
If we use the following excel code we got: "=T.INV(0.1,48)"
And the calculated value is
Step-by-step explanation:
State the null and alternative hypotheses to be tested
We need to conduct a hypothesis in order to determine if the true mean is lower than specified valu , the system of hypothesis would be:
Null hypothesis:
Alternative hypothesis:
Compute the test statistic
We don't know the population deviation, so for this case is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:
(1)
t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".
We can find the degrees of freedom for this test given by:
We know that the p value is 0.1, and since is a left tailed test would be given by:
And we can find the calculated value using excel or the t table.
If we use the following excel code we got: "=T.INV(0.1,48)"
And the calculated value is