What is the sum which earned interest?
I. The total simple interest was Rs. 7000 after 7 years.
II. The total of sum and simple interest was double of the sum after 5 years.
Choose the most appropriate option.
A) I alone sufficient while II alone not sufficient to answer
B) II alone sufficient while I alone not sufficient to answer
C) Either I or II alone sufficient to answer
D) Both I and II are necessary to answer
E) None of these
Explanation:   Let the sum be Rs. x.   I gives, S.I. = Rs. 7000 and T = 7 years.   II gives, Sum + S.I. for 5 years = 2 x Sum Sum = S.I. for 5 years.   Now, S.I. for 7 years = Rs. 7000.   therefore, S.I. for 1 year = Rs. 1000.   Thus, I and II both are needed to get the answer.   Answer: Both I and II are necessary to answer
<result>D</result>
What is the sum which earned interest?
I. The total simple interest was Rs. 7000 after 7 years.
II. The total of sum and simple interest was double of the sum after 5 years.