Aptitude - Problems on Ages - Discussion

Discussion Forum : Problems on Ages - Data Sufficiency 2 (Q.No. 3)
Directions to Solve

Each of the questions given below consists of a question followed by three statements. You have to study the question and the statements and decide which of the statement(s) is/are necessary to answer the question.


3.

What is the present age of Tanya?

I. 

The ratio between the present ages of Tanya and her brother Rahul is 3 : 4 respectively.

II. 

After 5 years the ratio between the ages of Tanya and Rahul will be 4 : 5.

 III. 

Rahul is 5 years older than Tanya.

I and II only
II and III only
I and III only
All I, II and III
Any two of the three
Answer: Option
Explanation:

  I. Let the present ages of Tanya and Rahul be 3x years and 4x years.

 II. After 5 years, (Tanya's age) : (Rahul's age) = 4 : 5.

III. (Rahul's age) = (Tanya's age) + 5.


From I and II, we get 3x + 5 = 4 . This gives x.
4x + 5 5

Tanya's age = 3x can be found. Thus, I and II give the answer.


From I and III, we get 4x = 3x + 5. This gives x.

Tanya's age = 3x can be found. Thus, I and III give the answer.


From III : Let Tanya's present age be t years.

Then Rahul's present age = (t + 5) years.

Thus, from II and III, we get : t = 4 . This gives t.
t + 5 5

Thus, II and III give the answer.

Correct answer is (E).

Discussion:
12 comments Page 1 of 2.

Vaidehi Mahale said:   9 months ago
Here, the last equation should be t+5/t+ 10 = 4/5 as we are considering the ages after 5 years.

AmanB said:   3 years ago
@All.

Let me explain;

Equation 1 and 2 & 2 and 3 will give the future after 5 years age.
i.e tania :20 year and rahul : 25 , because both consist equation 2 (which says after 5 years )

Whereas equation 1 will give the present age,
i,e. tania :15 , rahul : 20.

Hope you all get it , good day.
(1)

Tresuri said:   4 years ago
I don't understand this. Please anyone explain in detail.

Sachitra said:   4 years ago
I think the answer is wrong.
The correct answer will be (I, II & III) because,
3:4, we can take as 15 & 20.
4:5, as 20 & 25.
And here Rahul is 5 years older than Taniya.

A.GOPI said:   6 years ago
The present age of Tanya is 15 and Rahul is 20,
So Rahul is 5 years than Tanya,
So all statements correct.

JEEVAN said:   7 years ago
But if we use 2 and 3 how will we know?

Latha BV said:   8 years ago
After considering 2 & 3 statements we get the value of t and now we find the present age of Tanya, now we have to use the first statement so by using all 3 statements we get the present age of Tanya are else by using only 1 & 2 we get the present age of Tanya and by using 1 & 3 we get the present age of Tanya.

So the answer E is correct.

Krishna said:   8 years ago
Isn't t/(t+5) supposed to be in the ratio 3/4 since we are considering the present age?

Kasi said:   9 years ago
Take some x, then ratio = 3x+5/4x+5 after 5 years.

Then present ratio will (3x+5)/(4x+5) = 4/5, on solving we get x = 5.

Then there age will 15, 20.

Gayatree said:   1 decade ago
I am confuse that when to take different variable like x and y and when we have to take same variables like in this case.


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