Latest SSC Aptitude Question SOLUTION: The sum of how may terms of the series 6 + 12 + 18 + 24 + ... is 1800 ?

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(#M40009769) SSC Numerical Ability question Keep an EYE

The sum of how may terms of the series 6 + 12 + 18 + 24 + ... is 1800 ?

Asked In SSC Garima (12 years ago)

Solved chaitanya Read Solution (3)

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Read Solution (3) :

chaitanya  (12 years ago)

This is an A.P. in which a = 6, d = 6 and Sn = 1800

Then, n/2[2a + (n - 1)d] = 1800

n/2[2 x 6 + (n - 1) x 6] = 1800

=> 3n (n + 1) = 1800

=> n(n + 1) = 600

=> n2 + n - 600 = 0

=> n2 + 25n - 24n - 600 = 0

=> n(n + 25) - 24(n + 25) = 0

=> (n + 25)(n - 24) = 0

=> n = 24

Number of terms = 24.

Is this solution Helpfull? Yes (13) | No (2)  

phani  (12 years ago)

SOL:24

6+12+18+24+...............=1800
=>6(1+2+3+4+.............)=1800
=>(1+2+3+4+.............)=300
=>N(N+1)/2=300 SOLVING THIS N=24

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asim  (12 years ago)

24 terms of the given series gives sum 1800
since given series is in A.P with common difference (d) = 6 .
let no. of terms = n .
then
sum = n/2 [2*(first term) + (n - 1)*d]
on solving we get n = 24.

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