Which element of series equal to zero
Sir / Madam,
My questions is,
The sum of 3rd and 15th elements of an arithmetic progression is equal to the sum of 6th, 11th and 13th elements of the same progression. Then which element of the series should necessarily be equal to zero?
Advance Thanks,
R.Rengaraj
{InfosysTrain-Q103 Pg26}
My questions is,
The sum of 3rd and 15th elements of an arithmetic progression is equal to the sum of 6th, 11th and 13th elements of the same progression. Then which element of the series should necessarily be equal to zero?
Advance Thanks,
R.Rengaraj
{InfosysTrain-Q103 Pg26}
Replies
-
Saandeep SreerambatlaIs it the 12th element? -
rengarajSir,
Can you explain your answer?
R.Rengaraj -
Saandeep SreerambatlaI solved it in this way..
a+2d+a+14d = a+5d+a+10d+a+12d
2a+16d = 3a+27d
on solving it gives a+11d = 0
This it 12th element! -
rengarajSir,
Your answer matches with the available choices.
R.Rengaraj -
sherya mathurlets the first term of ap is a and difference is d
then third term will be =a+2d
15th will be=a+14d
6th will be =a+5d
11th will be =a+10d
13th will be=a+12d
then the equation will be as
a+2d+a+14d = a+5d+a+10d+a+12d
2a+16d = 3a+27d
a+11d=0
simply we can understand a+11d will be the 12th term of arithmetic progression
so the correct answer is 12
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