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Q:

# Puzzle : Bridge Crossing

#### Additional Details

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:
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

76
Q:

Which number multiplied by itself will give the output as 12345678987654321 ?

Answer

11 * 11 = 121

111 * 111 = 12321

what we observe is that the square of the number follows a pattern: 2 1's gives 121. 3 1's gives 12321.

so to get 12345678987654321 we need to get square of 9 1's(111,111,111).

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Subject: Math Puzzles

267
Q:

What 5 - digit number has the following features :

If we put the numeral 1 at the beginning, we get a number three times smaller than if we put the numeral 1 at the end of the number?

Answer

Let the 5 digit number be represented by abcde.

Then the 6 digit number, 1abcde x 3 = abcde1 (another 6 digit number)

Now let Y = abcde

Then (100000 + Y) x 3 = (Y x 10) + 1

300000 + 3Y = 10Y + 1

7Y = 299999

Y = 299999 ÷ 7 = 42857

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Subject: Math Puzzles

208
Q:

Arrange four nines(9) and a one(1) and only one mathematical symbol to make it equal to 100 ?

Answer

199 - 99  = 100

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Subject: Math Puzzles

344
Q:

In a Certain Country $\inline \frac{1}{2}$ of 5 = 3. If the same proportion holds, what is the value of $\inline \frac{1}{3}$ of 10 ?

 A) 4 B) 6 C) 8 D) 10

Answer & Explanation Answer: A) 4

Explanation:

Let $\inline \frac{1}{3}(10)=x$

$\inline \Rightarrow 3x=10$

Given that $\inline \frac{1}{2}(5)=3$

$\inline \therefore \frac{5}{2}(x)=10$

$\inline \Rightarrow x=4$

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Filed Under: Math Puzzles

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