What was the ledger balance in the saving bank account on January 31?

Question

(1) Had the increase in the ledger balance, from January 1 to January 31, in the saving bank account been 15 percent, then the ledger balance in the account on January 31 would have been $1150.

(2) From January 1 to January 31, the increase in the ledger balance in the saving bank account was 10 percent.

DavidTutorexamPAL · Answer

The answer is C.

We can solve this question  Logically  - by examining the type of data which is necessary to solve the question. 
Both statements describe a balance which changed between two dates (1st and 31st), meaning we have three variables: the original balance, the new one and the change between them.
As with any equation with three variables, we'll have to know two of them (the balance on the 1st and the change) in order to find the third (the balance on the 31st).

1) this is entirely hypothetical - since we don't know if the increase was indeed 15% or not, this tells us nothing about the balance on the 31st.
2) Without any data on the balance on the 1st, knowing the difference from that balance is insufficient.

Combined: (1) is sufficient to find the balance on the 1st (by dividing 1150 by 1.15). (2) gives us the change. Together, we have two variables out of three - sufficient!!

(to spell it out: the balance on the 1st is 1150/1.15= 1,000. the change is 10%. 1,000*1.1=1,100= the balance on the 31st)

Target4bschool · Answer

I am still confused about option A.

Let the actual balance be x. 
Then, 115x/100 = 1150 
So, x= 1000 --> sufficient.

IanStewart · Answer

You have found the balance on Jan 1st. The question asks for the balance on Jan 31st, and we need to know the change from Jan 1 to Jan 31 in order to answer that question, which is why we also need Statement 2.

Target4bschool · Answer

IanStewart I am sorry but I read it again...but still I am thinking the same

(1) Had the increase in the ledger balance, from January 1 to January 31, in the saving bank account been 15 percent, then the ledger balance in the account on January 31 would have been $1150

IanStewart · Answer

Part of the problem is that the wording of Statement 1 isn't perfect, but what it means is: "If the balance had increased by 15%, then on Jan 31st the balance would have been $1150". That doesn't tell you that the balance was $1150 on Jan 31st, just as the true sentence "if I earn a billion dollars this month, I will be a billionaire" doesn't mean I will be a billionaire at the end of the month. It just describes what would happen in one hypothetical scenario.

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What was the ledger balance in the saving bank account on January 31?

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