Answer: 21.3 miles
Step-by-step explanation:
Using the t-distribution, we have that the 95% confidence interval for the true mean number of pushups that can be done is (9, 21).
For this problem, we have the <u>standard deviation for the sample</u>, thus, the t-distribution is used.
- The sample mean is of 15, thus
. - The sample standard deviation is of 9, thus
. - The sample size is of 10, thus
.
First, we find the number of degrees of freedom, which is the one less than the sample size, thus df = 9.
Then, looking at the t-table or using a calculator, we find the critical value for a 95% confidence interval, with 9 df, thus t = 2.2622.
The margin of error is of:

Then:

The confidence interval is:

Then


The confidence interval is (9, 21).
A similar problem is given at brainly.com/question/25157574
Answer:
-4
Step-by-step explanation:
Let's put this in math notation. We can call the number x:
9x+4=8x
Subtract 8x from both sides:
x+4=0
Subtract 4 from both sides:
x=-4