Well if Abby is twice the age of her bother and her brother is 9 then she is going to be 18 because 9x2=18, then it says that she is half her dads age so all you have to do is add 18+18 which equals 36
Answer:

-- Sample Variance
--- Sample Standard Deviation
Step-by-step explanation:
Given


Solving (a): The sample mean

So:



Solving (b): Sample variance (s^2)
This is calculated as:

Where:

So:



Solving (c): Sample Standard Deviation (s)
This is calculated as:



Y=8.25x+10
10 is the allowance plus the 8.25 times x which is the hours
-1/2 / 3/4 =
The first step is to flip the second fraction and change division to multiplication. Then multiply straight across.
-1/2 x 4/3 = -4/6
In simplified form:
-4/6 = -2/3