# How to solve Puzzle part-4

## Lets talk about Puzzle

- There is a number that is 2 times the sum of its digits. What is this number?

for a two digit number say xy it is actually written 10x+y

so 10x+y=2(x+y)

=>8x=y

only possible when x=1 and y=8

so the required number 18

- If a clock takes 7seconds to strike 7, how long will the same clock take to strike 10?

The clock strikes for the first time at the start and takes 7 seconds for 6 intervals-thus for one interval time taken=7/6.

Therefore, for 10 seconds there are 9 intervals and time taken is 9*7/6=10 and 1/2 seconds.

Therefore, for 10 seconds there are 9 intervals and time taken is 9*7/6=10 and 1/2 seconds.

- A ship went on a voyage. After it had traveled 180 miles a plane started with 10 times the speed of the ship. Find the distance when they meet from starting point.

Say speed of ship=x miles/hour

Say they meet at 180+y miles.

so ship will take y/x hours to go there

by that time plane will cover the required distance 180+y and planes speed is 10 times of ship=10x miles

so (180+y)/10x=y/x

equating we will get y=20

so the the distance is 180+y=200 miles

- There is a 3 digit number. 3
^{rd}number is the square root of the 1st digit. 2^{nd}digit is the sum of 1^{st}and 3^{rd}.And that number is divisible by 2,3,6,7. What is that number?

where x=z*z-----1

y=x+z------2

and it is divisible by 2,3,6,7 i.e any multiplier of 2*3*6*7=42 that will satisfy the conditions

the three digit multiplier of 42

so the required number is 462

- A rich merchant had collected many gold coins. He did not want anybody to know about them. One day, his wife asked, "How many gold coins do we have?"After pausing a moment, he replied, "Well! If I divide the coins into two unequal numbers, then 37 times the difference between the two numbers equals the difference between the squares of the two numbers."The wife looked puzzled. Can you help the merchant's wife by finding out how many gold coins do they have?

Let, y and z be two numbers such that x = y + z (y not equal to z)

Given, 37(y - z) = (y^2) - (z^2)

Therefore, 37(y - z) = (y + z)(y - z)

Hence, total no. of gold coins= x = y + z = 37

Puzzle source-software_jobs yahoo groups

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