Answers

2015-12-26T15:28:10+05:30
4+8+12+16+20=60 
ans:60
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2015-12-26T15:43:11+05:30
Common difference (d) = (a2-a1)
                                      = (8-4) = 4
nth term = a+(n-1)d
    20 = 4+4n-4
    20 = 4n
    n = 5
an or last term (l) =  20
first term (a) = 4
sum (s) = n/2 (a+l)
              =  5/2 (4+20)
              = 5/2 (24)
              = 5 x 12 = 60
therefore, answer is 60.
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