13, 3. are the ones i could find
Two plus nine-teen is twenty one then you subtract seven from that and get fourteen. Your answer is 14 foot
15. 
Step 1: Distribute the subtraction sign to all the numbers in the second set of parentheses...


Step 2: Combine like terms (
's go with
's)




Step 3: Combine like terms (
's go with
's)




Step 4: Combine like terms (normal numbers go with normal numbers)

1 + 2
3

You were correct!
16. 
I don't really know how to explain this one but I got: (7m-6n)(7m-6n)
Step-by-step explanation:
3x - x = 2x
2(x + 2) = 2x + 2
for every number of x, 2x + 2 would always be larger than 2x.
so there is no solution, since the given equation is 2x is greater than 2x + 2.
Answer:
The 99% confidence interval for the difference between the true average load for the fiberglass beams and that for the carbon beams is (-11.937, -6.863).
Step-by-step explanation:
We have to calculate a 99% confidence interval for the difference between the true average load for the fiberglass beams and that for the carbon beams.
The sample 1 (Fiberglass), of size n1=26 has a mean of 33.4 and a standard deviation of 2.2.
The sample 2 (Carbon), of size n2=26 has a mean of 42.8 and a standard deviation of 4.3.
The difference between sample means is Md=-9.4.

The estimated standard error of the difference between means is computed using the formula:

The critical t-value for a 99% confidence interval is t=2.678.
The margin of error (MOE) can be calculated as:

Then, the lower and upper bounds of the confidence interval are:

The 99% confidence interval for the difference between the true average load for the fiberglass beams and that for the carbon beams is (-11.937, -6.863).