Puzzle 59 - How old is he?

-

Puzzle 1 : When asked his age, Jack tells that "In 2 years I will be twice as old as I was six years ago". How old is Jack now?


Puzzle 2: James  was  asked how old he is.  James said: “Five
years ago my Dad was five times older than me, but now he is only three times
older!” How old is James and how old is his father?


Solutions : 

1. If Jack's age is x, then

   x+2 = 2*(x-6)

   x+2 = 2x-12

2+12= 2x-x 

x = 14

Jack is 14 years old now.


2. If James's age is x and his father's age is y,

x*3 = y

and  (x-5)*5 = y-5

Substituting y with 3x in the above equation, we get

5x - 25 = (3x) - 5 

2x = 25 - 5 = 20

x = 10 and y = 30

So James is 10 years old and his father is 30 years old. 


Comments

Post a Comment

Popular posts from this blog

Puzzle 9 : The 4 coins problem

-
 Solution to puzzle 8: Maria is not counting Sundays. So she is not counting 1/7th of days of her age.  That is to say she is only counting 6/7th of her age. 6/7th of her age = 30 Her actual age = 30 X 7/6 = 210/6 = 35 years.  Puzzle 9 : The 4 coins problem  You’re creating a new coin system for your country. You must use only four coin values and you must be able to create the values 1 through 10 using one coin at a minimum and two coins maximum. What 4 coins do you choose, and can you think of a second set of 4 coins that achieves the same goal?
Read more

Puzzle 66 - solution

-
 The question was  What is wrong with this proof ? a=b multiply both the sides by a     --1 a2 = ab  add -b2 to both the side           --2 a2-b2 =ab-b2  factorizing                                --3 (a+b)(a-b) = b(a-b)  divide both the sides by (a-b)    ---4 a+b=b Substituting a with b,              ---5 2b = b Dividing both the sides by b    ---6 2 = 1   The problem is with step 4. When a is equal to b, a-b is zero. You can not divide numbers by zero because division is only defined for non-zero numbers.  
Read more

Puzzle 35 - Open sesame

-
I am writing a post after two months.  Here is a locked question ;) There is a number lock. You have to find the number to unlock it.  And here are the results of various number combinations. 682 - one digit is right and in the right position. 614 - one digit is right but in the wrong position. 206 - two digits are right but both are in the wrong positions. 738 - all digits are wrong. 380 - one digit is right but in the wrong place So what is the correct code to open the lock? Find the solution here
Read more