Latest exam Aptitude Question SOLUTION: The 12th term of an arithmetic series is 42 and the sum of the first 17 terms is 51. Find the common difference of the series, and find the first three terms of the series.

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(#M40097968) EXAM Numerical Ability question Keep an EYE

The 12th term of an arithmetic series is 42 and the sum of the first 17 terms is 51. Find the common difference of the series, and find the first three terms of the series.

Asked In exam (9 years ago)

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Devendra Marghade  (9 years ago)

Common difference=13 & first three terms are -101, -88, -75

If the first term=a and common difference=d, then
12th term of arithmetic series=a+11*d=42 ---(i) &
Sum of first 17 terms=(17/2)[2a+16*d]=51 or 34a+374d=1428 ---(ii)
From (i) & (ii), d=13, a=-101
So first three terms are -101, (-101+13=-88), (-88+13=-75)

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Satya B  (9 years ago)

12 th term= a+11d=42 -------2
sum of first 17 numbers= (17/2)(2a+16d)=51
2a+16d=6
a+8d=3 -------1
solving 1 & 2 we get d=13 a =-101
first three terms are -101 -88 -75

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