Its not a hard Mathematical question, it can be solved in few minutes, so did I. But I couldn't figure out proper equation and procedure to solve. could you help me out with it?
A father gave his son Rs 20 and asked him to get three things; books that cost Rs 5 each, notebooks that cost Re 1 each and pencils that costs 25p each. He also told him that he will be rewarded if total number of books, notebooks and pencils will be 20 too.
I would appreciate if you could post all procedure to work it out.

 

Your question is incomplete so it can be only solved by trail and error. Since your questions have 3 UNKONWS, there should be 3 equations to solve it. However, I can only make two equations.

Let us say he buys X number of Books, Y number of note books and Z number of pencil  each consting 5 Rs, Re 1 and  Rs 0.25  (25 P) each.

So,

5 X + Y + 0.25 Z  =  20

And second equation is total number of books, notebooks and pencil should be 20. so
X+ Y+Z = 20


Now where do we get 3rd solution from?  It can only be done by trail and error.

1. X is number of books each Rs 5.  However, it is impossible to buy 4 books since total number of books, note books and pencil should be 20 and he has only Rs 20.
2. If X is 3, Rs 15 is spend in 3 items. So we need to buy remaning 17 items in Rs. 5.  That is Y +0.25 Z =5
        now, follow similar procedure,
          (a)        If Y ( note book ) is = 1, then we can buy 16 pencils from remaining  Rs 4.

So the answer is 3 books, 1 note book and 16 pencils.


However, it is almost impossilbe to generate  an equation to solve your problem because it is just trial and error because of one missing equation.

no quiero,

The question is complete and you have answered the question correctly. There is only one solution, the one which is given by you. Your analysis is completely right but not complete.

using your notations and equations
5 X + Y + 0.25 Z  =  20
X+ Y+Z = 20

and there is another contrain that X,Y,Z should be positive, non zero integers (1,2,3 etc, not 5.3 and 10.6)

1. X is number of books each Rs 5.  However, it is impossible to buy 4 books since total number of books, note books and pencil should be 20 and he has only Rs 20.

Clever, so valid X could be, X = 1 or 2 or 3

For, X=3 we get Y +0.25 Z =5 and Y+Z=17
The solution X=3, Y=1 and Z=16 (your solution) is a valid solution because all are integers

For, X=2 we get Y +0.25 Z =10 and Y+Z=18
The solution X=2, Y=7.33 and Z=10.66 is NOT a valid solution because Y and Z are not integers, you can not buy 7.33 notebooks

For, X=1 we get Y +0.25 Z =15 and Y+Z=19
The solution X=1, Y=13.66 and Z=5.33 is NOT a valid solution because Y and Z are not integers

True Khaobadi.  However, it is not possible to  solve it by mathematical equations as asked by Ganapati  It is easier to do this mathematics because value of X is either of 1, 2, 3, 4.  What if X is 1000.

 

We cannot solve this by any equations. Because there are 3 Unkowns and only 2 equations.  Only thing we can resort is trial and error. Fortunately in this question there is ONE and Only one answer.

Normally, in  these types of  questions there are possiblitiy of set of answers and not single answer.  

here is a puzzle question...

how would u measure 7 pints of water using only a 3pint jug and a 5 pint jug ?

i will give answer tomorow.

I think no_quiero is correct when he said we need to do trial and error to get the answer and the answer from khaobadi is the result of that trail and error method.

gambler: 3 pints * 4 times - 5 pints * 1 time = 7 pints

If I understood your puzzle right,

1. Measure 4 X 3 pints

2. Take 5 pints out of the total 12 pints from step 1. (12-5 = 7)

3. Bingo!!! 7 pints remaining.

These puzzles might be interesting if you've not tried them before. They're quite ordinary though.

http://www.hkkccs.edu.hk/~tc02/math-games/game1.html

http://www.hkkccs.edu.hk/~tc02/math-games/game2.html

http://www.hkkccs.edu.hk/~tc02/math-games/game3.html

http://www.hkkccs.edu.hk/~tc02/math-games/game4.html

4  people  Ram, Laxman , Bharat Shatrughan  .  Ram takes 1 minute to cross a tunnel. Laxman takes 2 minutes, Bharat takes 5 minutes and Shtrughan takes 10 minutes to cross a tunnel.

Problem with tunnel was there is only place for 2 people to cross at one  time  and it was so dark they need a torch and they had only one torch.

 

In what order did they cross the tunnel so that all of them cross the tunnel within 17 minutes ?

norton & sumit

ur logic is right.. but it doesnt solve the puzzle.

u only have ONE 3pint jug and ONE  5 pint jug....    so it is not possible to do as u suggest.

the correct technique is easy, i will post it today evening or tomorow morning.

Ram(R) and Laxman(L) go first. Total Time = 2 minutes

R comes back. Total Time = 1 minute

Bharat (B) and Shatrughan (S) go with the torch. Total time = 10 minutes

L comes back with the torch. Total time = 2 minutes

R and L go to meet B and S on the other side of the tunnel. Total time= 2 minutes

Total time taken for all this = 17 minutes.

I think there are 3 vessels with capacity of 3 5 pints and a larger vessel where more than 7 pint is possible.

So fill 5 pint vessel, pour that to 3 pint vessel that leaves 2 pint in 5 pint vessel--- pour that to 7 pint vessel
repeat the same operation once again, so u have 4 pint in the larger vessel

fill 3 pint vessel once and add to the larger vessel that gives 4+3 = 7 pints

i think this is one of the solutions

N.M.

nepali manche u are very close to my answer

i will re-write the question.


There is the beautiful bagmati river flowing and if someone asks u to bring back exactly 7 pints of water using only a 3pint jug and a 5 pint jug ?

how would u do it.


hint - fill up 5 pint jug first.

nepali manche u are very close to my answer

i will re-write the question.


There is the beautiful bagmati river flowing and if someone asks u to bring back exactly 7 pints of water using only a 3pint jug and a 5 pint jug ?

how would u do it.


hint - fill up 5 pint jug first.

Fill the 5 pint jug.

Pour 3 pints of water from 5 pint jug in the 3pint jug.

Empty the 3 pint jug and pour the remaining 2 pints of water from 5 pint jug.

Now fill the 5 pint full of water.

Total water in two jugs is 7 pints.

 

gambler,

I think the solution is as follow if you only use 3 and 5 pints vessels:

1) Pour the water half-way on both vessels so that it'll be 1.5 pints of water on 3 pints vessel and 2.5 pints of water on 5 pints vessel.

2) Now, pour the water from 3 pints vessel to 5 pints vessel, so that the 5 pints vessel contains 4 pints of water (1.5+2.5=4).

3) Finally, pour the 3 pints of vessel full. Now, add the amount of water from both vessels (3 pints from 3 pints vessel and 4 pints from 5 pints vessel, which is 7 pints).

Another way,

Fill in 3 pint jug, pour it to 5 pint, fill in three again and pour it to 5. This leaves 1 pint in 3 pint with 5 pint full. Now empty 5, and pour 1 into 5. Now, Pour 3 into 5 twice. That leave 5 pint and 2 pint (in 3 pint jug). Total 7 pints, of course norton way is little easier.

and the award goes to NORTON... u did it my way... good job

LATOMANCHE u also came up with good suggestion....  i like your answer also.

both u guys solved it.

.