Step-by-step explanation:
After you find the sums for each set, make a list, counting the number of ways a sum can occur.
You'll notice that for Set A, sums of 5, 6, 7, 8, and 9 all appear 4 times. So they have equal probabilities. In Set B, a sum of 7 appears 6 times. Sums smaller or larger than 7 are less common.
When we look at the data, we see that were more sums of 7 than any other sum. So this data was probably from Set B.
Answers:

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Explanation:
By definition, 
Squaring both sides gets us 
Then multiply both sides by i to get 
Repeat the last step and you should get 
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Notice we have this pattern going on:

Once we reach i^4, we start the process over again.
It repeats every 4 terms.
This means we'll divide the exponent over 4 and look at the remainder. We ignore the quotient completely.
157/4 = 39 remainder 1
That remainder 1 is the exponent of the simplified term

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Similarly,
315/4 = 78 remainder 3
So 
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102/4 = 25 remainder 2

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76/4 = 19 remainder 0

Answer:
12a
3/4
34.8
a = 3.2
Step-by-step explanation:
9a + 6 = 34.8
9a = 28.8
28.8/9 = 3.2