SOLUTION: What should be added to make it 100. Take numbers between 4-38 only 5 digits required. Every number is at the distance of 4

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Question 824865: What should be added to make it 100. Take numbers between 4-38 only 5 digits required. Every number is at the distance of 4
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
We seek an arithmetic series of 5 terms with common difference d=4
such that S5 = 100

Sn = n%2F2[2a1 + (n-1)d]

S5 = 5%2F2[2a1 + (5-1)(4)]

100 = 5%2F2[2a1 + (5-1)(4)]

Multiply through by 2

200 = 5[2a1 + (4)(4)]

200 = 5[2a1 + 16]

200 = 10a1 + 80

120 = 10a1

 12 = a1

Answer = 12+16+20+24+28 = 100

Edwin