Answer:add then divide
Step-by-step explanation:
If you make a proportion,
12 18
--- = ---
10 x
when you cross multiply
12x=180
x=15
EF= 15
Answer:
The 99% confidence interval for the population mean is 22.96 to 26.64
Step-by-step explanation:
Consider the provided information,
A sample of 49 customers. Assume a population standard deviation of $5. If the sample mean is $24.80,
The confidence interval if 99%.
Thus, 1-α=0.99
α=0.01
Now we need to determine 
Now by using z score table we find that 
The boundaries of the confidence interval are:

Hence, the 99% confidence interval for the population mean is 22.96 to 26.64
Answer:
Step-by-step explanation:
Using the formula for calculating the distance between 2 points.
D = √(x2-x1)²+(y2-y1)²
Given
D = 45 units
The coordinates Q(–1, a) and P(3,2)
45 = √(3-(-1))²+(-2-a)²
45 = √4²+(-2-a)²
45 = √16+(-2-a)²
45² = 16+(-2-a)²
45² = 16+4+4a+a²
45² = 20+4a+a²
a²-4a+20-2025 = 0
a²+4a-2005 = 0
a = -4±√16+4(2005)/2
a = -4±√16+8020/2
a = -4±√8036/2
a = -4±90/2
a = -4+90/2
a = 86/2
a = 43
The possible values of a is 43
$10 / 6 = $1.67
total cost divided by number of books equals cost per book.