This cannot be determined because the distance between New York City and Alle City is not given.

Suppose the distance is x and the time it takes before the trains collide is t.
At time t one train will have travelled 15*t miles and the other one will have travelled 20*t miles.
The total will be 35*t miles and that will be x (x = 35*t => t = x/35)
At time t the bird will have flown 25*t miles which is 25/35 x = 5/7 x miles

Yes.
If Nile is married, he, as a married person,  is looking at the unmarried Senthil.
If Nile is not married, the married Ronni is looking at the unmarried Nile

R => N => S
M => M=> U
M => U=> U

There are three options when picking balls.

1) You pick 2 black balls. You remove them and replace them with one black ball. The total amount of black balls will decrease by 1 and the number of red balls stay the same.
2) You pick 2 red balls. You remove them and replace them with one black ball. The total amount of black balls will increase by 1 and the number of red balls will decrease by 2.
3) You pick a black and a red ball. You remove them and replace them with one red ball. The total amount of black balls will decrease by 1 and the number of red balls stay the same.

The number of red balls will always decrease by an even number (0 or 2).
The starting number of red balls is odd (13) and it will stay odd when you decrease it by an even number. So the number of red balls will never be 0.

The last ball will always be red.

You make pieces of 1, 2 and 4 units of gold.
The first day you pay with the 1 unit piece.
The next day you change the 1 unit piece for the 2 unit piece.
The third day you give the 1 unit piece again.
Day 4 you change both pieces for the 4 unit piece.
Next day you give him the 1 unit piece.
Day 6 you change the 1 unit piece for the 2 unit piece.
And on the last day you give him the 1 unit piece again.

Light one wire at one end and the other at both ends.
After 30 minutes the wire that is burning at both ends will be burned completely (1 hour/2).
The other wire will have 30 minutes remaining.
Now light the other end of that wire.
After another 15 minutes (30/2) that wire will also be burned completely.
Total time 45 minutes (30 + 15)

72 has the following factors 2*2*2*3*3

With these factors the following age combinations can be made:
1+1+72 = 74
1+2+36 = 39
1+3+24 = 28
1+4+18 = 23
1+6+12 = 19
1+8+9 = 18
2+2+18 = 22
2+3+12 = 17
2+4+9 = 15
2+6+6 = 14
3+3+8 = 14
3+4+6 = 13

Only two of them have the same sum: 2,6,6 and 3,3,8
With all the other combinations Jason would have known the answer with only the first two hints.
The last hint says that John has an oldest son.
With the ages 2, 6 and 6 John would have two “oldest sons”

So the correct answer is 3, 3, and 8.

After 12 months you still have one rabbit, if he didn’t die in those months.
In order to get babies you need at least one male and one female rabbit.

10

take the number, subtract 1 and multiply by 2

7 => 6 => 12
5 => 4 => 8
3 => 2 => 4
2 => 1 => 2
6 => 5 => 10

Teapot