Answer: Third option
Step-by-step explanation:
For this exercise it is important to remember the following:
1. By definition, the Associative property of addition states that it does not matter how you grouped the numbers, you will always obtained the same sum.
2. The rule for the Associative property of addition is the following (given three numbers "a", "b" and "c"):

Knowing the information shown before, you can identify in the picture attached that the option that illustrates the Associative property of addition is the third one. This is:

As you can notice that you will always get the same result:

Answer:

Step-by-step explanation:
we know that
To find the ratio of yellow to red marbles, divide the numbers of yellow marbles by the number of red marbles
Let
x-----> the numbers of yellow marbles
y----> he number of red marbles
we have

so

If you use a laptop: 9.25; a desktop with a CRT monitor: 55.51; a desktop with an LCD monitor: 46.26.
A laptop that is plugged up and turned off uses 0.001kw/hr of energy. Each kwh of energy produces, on average, 1.39 lbs of CO2. There are 24*7=168 hours in the week; subtract the 40 hour work week from this and we have 128 hours a week for 52 weeks a year:
0.001*128*52=6.656*1.39=9.25.
A desktop that is plugged up and turned off uses 0.004kw/hr of energy. A CRT monitor uses 0.002 kw/hr when turned off. This means we have:
(0.004*128*52*1.39)+(0.002*128*52*1.39)=55.51.
For a desktop and an LCD monitor, which uses 0.001 kw/hr of energy, we have:
(0.004*128*52*139)+(0.001*128*52*1.39)=46.26.
There are 10 letters in the set {a, b, c, d, e, f, g, h, i, j} which is the pool of letters to choose from when making these three letter codes.
We have 10 choices for slot 1
Then 9 choices for slot 2. This is because we can't reuse the choice for slot 1
Then 8 choices for slot 3
Overall, there are 10*9*8 = 90*8 = 720 different permutations
Answer: 720
Note: you can use the nPr permutation formula with n = 10 and r = 3 to get the same answer