**Bob** buys two things in a shop. With his pocket calculator he calculates in advance what he has to pay: **5.25 dollars.** But what he does not notice is that he pressed the **division **instead of the **addition **button. At the desk he is not surprised if he hears that he has to pay **5.25** dollars.
What is the price of the two things **Bob **has bought?

**Know the cost of those 2 things.**

**What was the mistake?**
Let's assume that those things costs **a** and **b** respectively.

As per Bob's wrong calculation,

a / b = 5.25

**a = 5.25 b **..........(1)

And according to what should have been correct,

**a + b = 5.25**

Putting (1) in above,

5.25b + b = 5.25

6.25b = 5.25

**b = 0.84**

Again putting this value in (1) gives,

a + 0.84 = 5.25

a = 5.25 - 0.84

**a = 4.41**
** **

Hence the cost of 2 things are **$4.41** and **$0.84.**
In a contest,** four** fruits (an apple, a banana, an orange, and a pear) have been placed in four **closed** boxes (one fruit per box). People may guess which fruit is in which box. **123 **people participate in the contest. When the boxes are opened, it turns out that **43** people have guessed** none** of the fruits correctly, **39** people have guessed **one** fruit correctly, and **31** people have guessed** two** fruits correctly.

How many people have guessed** three **fruits correctly, and how many people have guessed **four** fruits correctly?
**Escape to answer without getting tricked!**
**What was the game?**
There is absolutely** no way** that somebody has guessed **3** **correctly** since if 3 are correct then 4th has to be correct. Hence, nobody guessed 3 correctly.

So number of people with all 4 guess correct is equal to **123 - 43 - 39 - 31 = 10.**

**10 people** guessed all the** 4 fruits correctly.**** **

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** 32 time**s 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 they have?
**Here are mathematical steps to find those!**
**What was that clue?**
Since when divided into 2 unequal numbers difference won't be 0. Let x and y be the 2 unequal numbers.

As per merchant,

**32 (x - y) = x^2 - y^2**

32 (x - y) = (x - y) (x + y)

Dividing both sides by** (x - y)** which is non zero as **x** is **not equal** to** y,**

32 = x + y

**x + y = 32.**

Let's verify with x = 30 and y = 2. So 32 (x - y) = 32 ( 30 - 2) = 896. And x^2 - y^2 = 30^2 - 2^2 = 900 - 4 = 896.

Hence, Merchant had **32 coins** in total.

Whether it’s possible to construct a **magic square** using the first nine** prime** numbers (here counting 1 as prime):

1 2 3 5 7 11 13 17 19

Is it?

**Find the possibility here!**
**What was the task given?**
That's** impossible** task. All the listed** prime numbers** sums together to** 78**. For **square** to be magic, sum of each row & column must be equal. In this case, it should be **78/3 = 26.**

For sum of** 3 **to be **even**, **1 **must be **even** & other **2 odd** (or all even). All **3 odd **can't sum **even.**

In listed prime numbers there is only 1 even number i.e.2. Hence, for other 2 rows/columns we can't have **even** **sum.**
There is an** Island** of puzzles where numbers** 1 - 9** want to **cross** the river.
There is a **single boat** that can take numbers from one side to the other.

However, **maximum 3 **numbers can go at a time and of course, the boat cannot sail on its own so one number must come back after reaching to another side.

Also, the** sum** of numbers crossing at a time must be a** square** number.

You need to plan trips such that **minimum** trips are needed.
**This should be that minimum number!**
**What was the challenge?**
We need only** 7 trips** to send all digits across the river.

1. Send 2, 5, 9 (sum is 16).

2. Bring back the 9.

3. Send 3,4, 9 (sum is 16).

4. Bring back the 9.

5. Now send 1,7,8 (sum is 16).

6. Bring back the 1.

7. And finally send 1,6,9** **(sum is 16).
A **prisoner** is faced with a decision where he must open one of **two** doors. Behind each door is either a **lady** or a **tiger.** They may be **both** **tigers,** **both ladies** or one of each.

If the prisoner opens a door to find a lady he will **marry** her and if he opens a door to find a tiger he will be eaten alive. Of course, the prisoner would prefer to be married than eaten alive :).

Each of the doors has a** statement** written on it. The statement on door one says,* “In this room there is a lady, and in the other room there is a tiger.”*

The statement on door two says,* “In one of these rooms there is a lady, and in one of these rooms there is a tiger.”*
* *

The prisoner is informed that one of the statements is** true** and one is **false.**

Which door should the Prisoner open?
**This should be his choice!**
**What were the choices?**
For a moment, let's assume that **first statement** is** true.** The lady is behind the** Door 1** and tiger is behind the **Door 2.** But this makes** statement 2** also **true **where it says there is tiger behind one of these door & lady behind one of these doors. Hence, the **statement 1** can't be **true.**

Hence, statement 2 must be true.

Only possibilities left are -

**Door 1** - Tiger

**Door 2** - Tiger

**Door 1** - Lady

**Door 2** - Lady

**Door 1** - Tiger

**Door 2** - Lady.

Since, the true second statement is suggesting there is lady behind 1 & tiger behind the other door, the possibilities of both tigers or ladies are eliminated.

That's why behind** Door 1** is **tiger** & behind** Door 2** is** lady.**
** **** **