Math Puzzles Questions

First weigh 3 against 3 balls. If the ball contains among these six balls, then take the three balls which weighed over, and weigh the ball 1 against 1. If the balls are not equal and any one of the ball weighs more, that is the overweight ball, else the one among the three which is not weighed is the ball. If the 3 against 3 balls were equal, then weigh the 2 balls, then the overweight ball will be found.

First Jim and Jeanne walks across the bridge, it takes 2 minutes. 

Jim walks back with the torch light, which takes 1 minute. 

Then Louis and Anne walk on the bridge, which takes 10 minutes.

Jeanne comes back with the torch light, it takes 2 minutes.

Finally Jim and Jeanne walks across the bridge, which takes 2 minutes.

Total = 2 + 1 + 10 + 2 + 2 = 17 minutes

Non collision can happen only when all the cars move in same direction.

That is either all cars moving in clockwise direction or all cars moving in anti clockwise direction.
P(all cars not colliding)

= P(all cars moving in the same direction)

= P(all cars moving in clockwise direction)  +  P(all cars moving in anticlockwise direction)

= [p(A --> C) x p(C --> B) x p(B --> A)]  +  [p(A --> B) x p(B --> C) x p(C --> A)]

= [1/2 x 1/2 x 1/2] + [1/2 x 1/2 x 1/2]

= 1/8 + 1/8

= 1/4

  Zero. You are selecting names from the list, so they are all listed.

In the given puzzle the logic is

2 x 1 + 1 = 2 + 1 = 3

3 x 2 + 2 = 6 + 2 = 8

4 x 3 + 3 = 12 + 3 = 15

5 x 4 + 4 = 20 + 4 = 24

6 x 5 + 5 = 30 + 5 = 35

Similarly,

7 x 6 + 6 = 42 + 6 = 48

7 = 48.

Let the required number be 'N'

given that its quarter i.e; N/4 exceeds its double i.e, 2N by 7

=> N/4 + 7 = 2N

=> N + 28 = 8N

7N = 28

N = 4.

(1+9+6+8+3) x (1+9+6+8+3) x (1+9+6+8+3) = 19683

Except 142 all are divisible by number '7'.