Answer: 
Step-by-step explanation:
For this exercise it is important to remember the following:
1. By definition, the "Product" is the result of a multiplication.
2. The "Difference" is defined as the result of a subtraction.
3. The Distributive property states that:
Keeping the above on mind, you know that:
"The difference of 
and 
" can be represented with the following expression:
Therefore, "The product of -13 and the difference of and " can be represented with this expression:
Finally, you must apply the Distributive property in order to simplify the expression. You get:
Step-by-step explanation:
ما زلت لا أستطيع أن أخبرني بما تحاول أن تخبرني به ولد أو بنت آسف على تحمله
Markup = $4
b) markup as a percentage of cost is 33.3%
Step-by-step explanation:
Markup
markup = selling price - cost
= $13 - 9
... markup = $3
Markup as a Percentage of Cost
To find the percent markup, divide the markup by the reference value and multiply the ratio by 100%. The reference value for markup is usually cost price, but sometimes may be selling price.
... markup / cost × 100% = 3/9×100% = 33 1/3% ≈ 33.3%
12/6 + 2/3 + 3/4
MMC of 6, 3 and 4 is 12
So 24+8+9/12 = 41/12 = 3,41 approximately.
Answer: a. n= 1068
b. n= 164
Step-by-step explanation:
The formula to find the sample size :
, where p=prior population proportion , z* = critical z-value and E = Margin of error.
Here , let p=proportion of computers that use a new operating system.
Given : Confidence level = 95%
i.e. z* = 1.96 [by z-table]
Margin of error : E = 3% =0.03
a. If p is unknown , then we assume p=0.5
Then, 
i.e. n= 1068
b. p=0.96
Then, 
i.e. n= 164.
