Answer:
15n
Step-by-step explanation:
Amal has a bookcase with n shelves. There are 15 books on each shelf. Using n, write an expression for the total number of books.
The expression for the total number of books is given as:
Number of shelves × Number of books in each shelf
= n × 15 books
= 15n
<h2>
Answer</h2>
This answer is 18y • (y - 1)
<h2>
Explanation</h2>
Step by step solution:
Equation at the end of step 1:

Equation at the end of step 2:

Equation at the end of step 3:

Equation at the end of step 4:
After performing basic +, - operation we get:

Answer is: 18y. (y – x)
Answer:
a. no, there are no sufficient data to use
b. assumption b is right
Step-by-step explanation:
a. for the standard deviation to be calculated at 99% confidence, the data needed should be the mean (given), the variate value to be calculated for(not given), the standard deviation(not given), the z value of the normal distribution ( not given),
since there are too many unknown, the data given are not sufficient to calculate.
b. validity of this interval requires that coating layer thickness be at least approximately normally distributed.
You basically simplify for this one,18 / ? = 9
18/2=9
So in this case, 8*2 is 16! Hope this helps!