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.

first press the first switch and leave it for 5 mins then turn off that switch and turn on another switch for 2 mins and switch off that one also now finally switch on the third one and enter in to the room.

the lighting bulb is the third one and remaining 2 is:

Touch the bulb,  the bulb which has high heat is 2nd switch  one and which has less heat is the first switch.

i think i m correct .

No Quiero,

Room # A: Say, Swiches 1, 2 ,& 3.

Room# B; Say, Bulbs B1,B2 & B3 that correspond to Switches 1, 2 & 3 respectively.

-  Go to Room A and turn on switches 1 & 2 (leave switch 3 turned off).

- After few minutes turn off switch 2

- Now go to Room# B. You will see one of the bulbs lighting ie. A1- that corresponds to Switch 1

- Now touch remaining two bulbs i.e. A2 and A3.

- You will find bulb# A2 hot, as the switch # 2 was momentarily switched on.

-  You will feel A3 cold, as the switch # 3 was never turned on. 

So easy

1, 2, 6, 42, 1806, 1180482

This one is simple the series is the number n multiplied by n+1

1, 1*2, 2*3, 6*7, 42*43, 1806*1807.............

The answer could be :

First Son:       (1) 11 + (2) 22 + (3) 33 + (4) 44 +  (5) 55 = 165 ltrs (5 cows)

Second Son:  (6) 66 + (9) 99                                           = 165 ltrs (2 cows)

Third Son:      (7) 77 + (8) 88                                           = 165 ltrs (2 cows)

But this combination is quite unequitable because one of the sons has to feed 5 cows to get 165 ltrs of milk whereas other two sons can get the same amount of milk by feeding only two cows each.

Now the fair distribution would be:

First Son:         (1) 11 +(6) 66 + (8) 88 = 165 ltrs

Second Son:    (2) 22 + (4) 44 + (9) 99 = 165 ltrs

Third Son:       (3) 33 + (5) 55 + (7) 77 = 165 ltrs

Note: The numbers in parantheses indicate the ith number of cow, where i = 1, 2, 3...............,9.