O boy…I will come back to this when it’s not so late (lol) My brain is too tired for this rt now, but this is engaging & fun – thx for sharing! When u went thru these how many did u get right?
Dushyant, the whole idea is to think about it a little, visualise the situation, understand how it behaves. I am advocating this approach precisely because such problems would be all the more difficult with equations.
In the first problem, for example, start by taking a few values for the ages and see how the system behaves. For example imagine that if A and B are today 30 and 25, what will be B’s age when A is B’s current age (i.e. 25)? He will be 20, right? And simlarly if today A and B are 28 and 22, then when A was 22, B would have been 16. But 25 is the average of 20 and 30, and similarly 22 is the average of 16 and 28. In this manner we can realise that a statement like “when I was as old as you are now” means that if the current ages are x+a and x, then the older ages were x and x-a. If you can’t visualise this, then you can’t solve it orally – but if you can, then it is easier to do orally than with equations. I cannot make you visualise it 🙂 I can only ask you to try!
Do the same for the second question, take two salaries in the ratio 3 : 4 and subtract values in a ratio more than 3 : 4 from both numerator and denominator. See what happens, check the new ratio – convince yourself that it will always be less than 3 : 4. Then take the trouble to understand why (read up on componendo, dividendo and similar concepts)
To apply the methods I will be talking about in the next few posts, your conceptual clarity has to be superb. If your understanding is ironclad, then you can do seemingly miraculous stuff without writing a thing….else you will be condemned to stare at equations.
You mean the Ram and Shyam question right? Well, the official answer given did actually calculate it from the given information. It was a good 6-8 minute solution though, so it would be a well-left problem without options.
I have interpreted question 1 as when the person A being four times older than person B at the time when person A was age of person B today.so on using the options i got 12 as answer.
B s current age is 12 then A should be 21 now
When A is 12 then B will be 3 years(12-9).
At that time age of a is four times of B.
Could you kindly explain me where i am getting wrong?
CAT-holics 
O boy…I will come back to this when it’s not so late (lol) My brain is too tired for this rt now, but this is engaging & fun – thx for sharing! When u went thru these how many did u get right?
Hi
Can you please elaborate on question 1 and 2 ? I didn’t get (how to solve) even with pen and paper. 😦
Dushyant, the whole idea is to think about it a little, visualise the situation, understand how it behaves. I am advocating this approach precisely because such problems would be all the more difficult with equations.
In the first problem, for example, start by taking a few values for the ages and see how the system behaves. For example imagine that if A and B are today 30 and 25, what will be B’s age when A is B’s current age (i.e. 25)? He will be 20, right? And simlarly if today A and B are 28 and 22, then when A was 22, B would have been 16. But 25 is the average of 20 and 30, and similarly 22 is the average of 16 and 28. In this manner we can realise that a statement like “when I was as old as you are now” means that if the current ages are x+a and x, then the older ages were x and x-a. If you can’t visualise this, then you can’t solve it orally – but if you can, then it is easier to do orally than with equations. I cannot make you visualise it 🙂 I can only ask you to try!
Do the same for the second question, take two salaries in the ratio 3 : 4 and subtract values in a ratio more than 3 : 4 from both numerator and denominator. See what happens, check the new ratio – convince yourself that it will always be less than 3 : 4. Then take the trouble to understand why (read up on componendo, dividendo and similar concepts)
To apply the methods I will be talking about in the next few posts, your conceptual clarity has to be superb. If your understanding is ironclad, then you can do seemingly miraculous stuff without writing a thing….else you will be condemned to stare at equations.
regards
J
I totally understood the concept (I can imagine now how I am getting older 😛 ).
Thanks for writing such great posts. 🙂
A really good post
Hello Sir,
Thanks for the awesome posts. 🙂
I have a query in the last sum. Suppose, the options were not given, is it possible to determine the actual answer with the given information?
Sorry sir, but the query is for Writer’s Block-3
You mean the Ram and Shyam question right? Well, the official answer given did actually calculate it from the given information. It was a good 6-8 minute solution though, so it would be a well-left problem without options.
regards
J
Cool. Thank you sir.
Hello J,
I have interpreted question 1 as when the person A being four times older than person B at the time when person A was age of person B today.so on using the options i got 12 as answer.
B s current age is 12 then A should be 21 now
When A is 12 then B will be 3 years(12-9).
At that time age of a is four times of B.
Could you kindly explain me where i am getting wrong?
“I am 4 times as old as you were” so A’s present v/s B’s past. Your interpretation would be “I was 4 times as old as you were”…
regards
J