1-5:These questions are based on the following data

I was visiting my friend's house at Tuticorin for the first time. I knew that he has five children, two daughters and three sons. The daughters were Sonali and Monali and the sons were Surya, Sagar and Prithvi. When I stepped into the house I was greeted by Sagar and Sonali. Sagar introduced himself and told that he was twice as old as Sonali.The next to meet me was Monali who said that she and Sonali together were twice as old as Sagar. However Sagar felt relieved when Surya walked in and introduced himself and said that he and Sagar were twice as old as their sisters together. In the afternoon Prithivi came to my room when I was relaxing and said "Sorry Uncle, I was busy with my friends, since it is my 21st birthday today and hence could not meet you in the morning" When greeted him and said that it was fine, he looked relieved and said "you know uncle, that the three of us Sagar, Surya and me are five times as old as our sisters together" saying this he went away

1.What is the age of Surya?
(a)4 yrs (b)4 yrs 3 months (c)8 yrs (d)10 yrs 6 months

2.What is the age of Monali?
(a)4 yrs (b)4 yrs 6 months (c)5 yrs (d) 5 yrs 3 months

3.Who is the youngest of the siblings?
(a)Surya (b)Monali (c)Sonali (d)None of these

4.How amny yrs older than Sonali is Monali?
(a)3 yrs (b)3yrs 6 months (c)5 yrs 6 months (d)7 yrs

5.After how many yrs would Surya be twice as old as Sagar?
(a)2 yrs (b)2 yrs 6 months (c)3 yrs 6 months (d)It is not possible



sol: These type pf questions first assume the age as x or some parameter from the starting

Let Sonali's age be 'x'

Sagar introduced and said he was twice as Sonali so '2x'

Next, let Monali's age be 'y'

she said she and Sonali together is twice as Sagar so => x+y=2(2x)

=>y=3x;
Let the surya's age be 'z'
He said he and sagar are twice as old as his sisters =>z+2x=2(x+y)

=>z=2y;

Prithvi's age is 21 he mentioned there

He said he sagar and surya are 5 times older than their sisters

=>2x+2y+21=5(x+y)
=>21=3(x+y)
=>x+y=7

We know that y=3x => x=7/4 => 1 yr 9 months(Sonali's age)
Sagar's age=2(7/4)=3 1/2 yrs
Monalis age=3*(13/4)=5 1/4 yrs
Suray's age=6(1 3/4)=10 1/2 yrs