Question 430098
A boy was offered a bonus if he sold 100 subscriptions to a magazine.
Each day he sold 3 subscriptions more than he had on the previous day, and on the 8th day he reached his 100 quota. 
How many subscriptions did he sell each day?
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Arithmetic Sequence with common difference = 3
and S(8) = 100
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Solve:
S(8) = (8/2)(1st + last)
100 = 4(1st + last)
1st + last = 25
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a(n) = 1st+(n-1)d
last = a(8) = 1st+7*3
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Solve:
1st+ [1st+21] = 25
2*1st + 21 = 25
1st = 2
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1st day: 2
2nd: 5
3rd: 8
4th: 11
5th: 14
6th: 17
7th: 20
8th: 23
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Sum = 100
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Cheers,
Stan H.