Math Puzzles Questions

Q:

Puzzle : Identical Balls

There are 8 identical balls. In that one of the ball is overweight. There are only two chances to weigh in the weighing machine. How to find the overweight ball?

Answer

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.

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Subject: Math Puzzles

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Q:

In a certain city, 5% of all the persons in town have unlisted phone numbers. If you select 100 names at random from that city's phone directory, how many people selected will have unlisted phone numbers?

Answer

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

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Subject: Math Puzzles

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Q:

Math Challenge

find the number maths puzzle

A) 7 B) 44
C) 4 D) 33
 
Answer & Explanation Answer: C) 4

Explanation:

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.

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Q:

Replace each letter for a unique digit so that the equation is correct

Answer

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

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Q:

Puzzle : Bridge Crossing

Jim, Jeanne, Louis and Anne wants to cross the bridge at night. They have only one torch light with them. Only two can cross the bridge at a time. They need torch light to cross the bridge. Each of them walks at a different speed. Jim needs 1 minute, Jeanne needs 2 minutes, Louis needs 5 minutes and Anne needs 10 minutes. A pair must walk together at the rate of the slower person. How these people can cross the bridge within 17 minutes?

Answer

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

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Subject: Math Puzzles

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Q:

What is the Probability of all cars not clashing each other ?

triangular1504515041.jpg image

A) 1/8 B) 0
C) 1/4 D) 1
 
Answer & Explanation Answer: C) 1/4

Explanation:

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

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Q:

Find the ODD number ?

odd1502270940.jpg image

A) 42 B) 142
C) 119 D) 21
 
Answer & Explanation Answer: B) 142

Explanation:

Except 142 all are divisible by number '7'.

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Q:

Can you slove this Maths Puzzle?

maths_puzzle1537500715.jpg image

A) 12 B) 6
C) 3 D) 1
 
Answer & Explanation Answer: B) 6

Explanation:

In the given puzzle, the logic behind is

9 = 72 => 9 x 8 = 72

8 = 56 => 8 x 7 = 56

7 = 42 => 7 x 6 = 42

6 = 30 => 6 x 5 = 30

5 = 20 => 5 x 4 = 20

 

Similarly,

4 = 12 => 4 x 3 = 12

3 = 6 => 3 x 2 = 6

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