GMATprep

[veekay]

Can anyone provide a better approach to solve this one? I almost took 5 minutes to solve this

[Bharat]

Given series is an A.P.
for any AP; Tn = T1 + (n-1)d
here d = -3
T1 = 23
& Tn = -4

On solving: n = 10

I believet that this is the fastest solution, however, I am eager to know if there is a still faster approach.

[veekay]

Given series is an A.P.
for any AP; Tn = T1 + (n-1)d
here d = -3
T1 = 23
& Tn = -4

On solving: n = 10

I believet that this is the fastest solution, however, I am eager to know if there is a still faster approach.

Thanks Bharat. I was not interpreting it that way. I thought series first increases from t1 to tn and then decreases to t1 and it sum is 23

Not sure how I got the right answer.

This is straigh forward.