IPMAT/Algebra•8mos
radharaman_108

Sequence and SERIES

How to solve this?

1

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Comments (4)

E
economisttoiimidr
•8mos

its basically repetitions in the sequence of 1,2,3,... till 400 so sn>=400 so n is our 400th term

2
R
radharaman_108
OP•8mos

but how?

0
E
economisttoiimidr
•8mos

its basically 1 getting repeated once , 2 twice , 3 thrice and so on

0
I
ipmatter2atharv
•7mos

Ignore what term is in the series treat each term as one object now if u look logically the series became 1 object+2 objects+3 objects and so on. Here we have to find a Sum of nth term of Ap(1,2,3...) which is greater than 400 as Sum of n-1 term is less than 400 so the formula will be (n(n+1))/2 > 400 now dont solve this instead put value by trying 2_3 times u will land on 28*29/2

Hence ans is 28

1