Aptitude - Average - Discussion

Good method to solve such type of question.

No need to add 3 to all.

You have add 3 to avg it give avg age of all.

Then age of three number = 30*3 = 90.

Then add 5 to avg age of child and wife it gives present age i.e. 25.

Age of two persons = 25*2 = 50.

Age of husband = total age - two members age.

90 - 50 = 40.

Let husband present age - x.
Let wife present age - y.
Let son present age - z.

The average age of husband, wife and son before 3 years was 27.

i.e Before 3 year (x-3)+(y-3)+(z-3)/3 = 27.

x-3+y-3+z-3 = 27*3.
x+y+z = 81+9.
x+y+z = 90.....(1).

The average age of wife and son before 5 years was 20.

i.e Before 5 years (y-5)+(z-5)/2 = 20.

y-5+z-5 = 20*2.
y+z = 40+10.
y+z = 50....(2).

Now by subtracting equation 2 from equation 1, we will find x = 40.

1. Before 3 years husband+wife+child = 27.

Now = 30*3 = 90.

2. Before 5 years wife+child = 20.

Now = 25*2 = 50.

Husband age = 90-50 = 40.

Let age of husband, wife and child is x, y, z.

Then 3 year ago age of husband, wife and child was x-3, y-3, z-z.

Given that 3 year ago average of their age was 27.

So (x-3+y-3+z-3) /3 = 27.

=> x+y+z-9 = 81.

=> x+y+z = 90____ (1).

5 year ago age of wife and child was y-5 and z-5.

Given that 5 year ago average of their age was 20.

So (y-5+z-5)/2 = 20.

=> y+z-10 = 40.

=> y+z = 50_______ (2).

Now, (1) - (2).

=> x = 40.

So age of husband is 40.

Ramya it is very easy to understand. Keep solving the problem in the easiest way.

@Swathi

Answer for the !st problem.

Given :
1) Going to destination:
Distance = 27 miles.
Speed = 18mph.

2)Return journey:-
Distance= 27 miles
Speed=50% faster than 18mph(given).
So, Speed = 1/2*18 + 18 = 27.
Speed =27mph.
Halt of bus=30 minutes.

Answer:-

Let's first find the time to reach the destination:-
Speed = Distance/time
So, time = Distance/Speed
Time =1.5 hr.

Let's find time to return
Time = Distance/Speed
=27/27.
= 1 hr.

So total time taken to go and return
= going time + 1/2 hr (halt) + return time.
= 1.5 + 0.5 + 1 hr.
= 3hr.

So as journey began at 8 am
So Bus will return at 8am+ 3hr=11am.
Final Answer : a) 11am.

@Swathi

Answer for the 1st problem.

Given :
1) Going to destination:
Distance = 27 miles.
Speed = 18mph.

2)Return journey:-
Distance= 27 miles
Speed=50% faster than 18mph(given).
So, Speed = 1/2*18 + 18 = 27.
Speed =27mph.
Halt of bus=30 minutes.

Answer:-

Let's first find the time to reach the destination:-
Speed = Distance/time
So, time = Distance/Speed
Time =1.5 hr.

Let's find time to return
Time = Distance/Speed
=27/27.
= 1 hr.

So total time taken to go and return
= going time + 1/2 hr (halt) + return time.
= 1.5 + 0.5 + 1 hr.
= 3hr.

So as journey began at 8 am
So Bus will return at 8am+ 3hr=11am.
Final Answer : a) 11am.

Thanks for your easy explanation @Loverboy.

@Ramya.

Really a great explanation. Thank you.