Hi Swarman,
There are two things wrong with this method.
Firstly, when you combine both the statements together, you get the value of n t be less than -5. However, we know that n denotes the number of set of books and thus, cannot be negative. So, the answer does not stand. However, what this negative value does tell you is that the value of c is not 200.
Secondly, while evaluating the first statement you got c=200 because you considered all three sets of encyclopedias to be above the sales target of n sets. However, there are three possibilities.
1. All three of them are above the sales target in which case 3c=600 implying c=200
2. Two of them are above the sales target in which case 2c=600 implying c=300
3. Only one of them is above the sales target in which case c=600
Since, one is already proved to be wrong, the answer has to be one out of 2 and 3. Substituting c=300 in the statement 2 gives us a value of n=0. Hence, not possible.
The answer is the c=600 and hence we need to use this value to work further with this problem.
Hope this helped! Let me know in case of any further doubts/concerns.
swarman wrote:
Hi all,
I would be grateful if you could pls tell answer my query. I totally understand Buneul's approach but i wanted to ask, why is it done that ways?as in why do we have to take three cases? why cant we do it like the question says her income would be equal to 1000+c(s-n)
as per statement 1:
assuming the no of sets she sold in march as M the equation of net income turns out to be as
--> 1000 + c(M-n) - [1000 + c(M-3-n)]=600
=>3c=600
=>c=200
which doesnt seem sufficient to estimate her sales in March Hence insufficient.
As per statement 2:
1000 + c(10-n)>4000
again insufficient
Using both statemnt 1 &2 we get value of n as < -5, which is invalid as per given conditions. Hence answer is E
kindly tell me where i m going wrong in this approach!