In the case of d=0 all the terms will be same then we if we consider first term as ‘a’ then tenth term will also be ‘a’ and hence the ratio will be 1:1.
Is there any error in my reasoning here?
Yes ideally the question should have stated “with distinct terms”. The original CAT question did not, but then there were options there…
CAT-holics 
In the last problem d can also be 0 in which case all the terms will be the same
Nice spot Chirag. However, in that case the ratio of terms will not even be defined!
regards
J
Hi j,
In the case of d=0 all the terms will be same then we if we consider first term as ‘a’ then tenth term will also be ‘a’ and hence the ratio will be 1:1.
Is there any error in my reasoning here?
Yes ideally the question should have stated “with distinct terms”. The original CAT question did not, but then there were options there…
regards
J