Maths Riddles

The girl was born on 29 February, thus she put 250 stamps every four years.
In forty years, she put stamps only 10 times which makes the total of 2500 stamps.
Her sister was born on any other day and she took out 50 stamps from the box forty times which makes the total stamp she took out to be 2000.

Thus after forty years, the girl’s box had only 500 stamps.

Did you think of paper?
Well that will be a wrong answer as a piece of paper has 6 surfaces as the edges are also counted as surfaces only no matter how thin they are.

The correct answer is a cone.

54
7^2 + 2^2 + 1^1
6^2 + 3^2 + 3^2
2^2 + 5^2 + 5^2

DAVID

Talking in roman numerals,
D = 500
At the center is 5 = V
The first number is I
The first letter of the alphabet is A

Thus they combine to form DAVID.

First of all, he will have to make three trips of 1000 mangoes till 333 miles. After that, he will be left with 2001 mangoes and 667 more miles to go.

Then he must take two trips of 1000 mangoes covering 500 miles more. Doing this, he will be left with 1000 mangoes and 167 remaining miles to reach the town. (He will have to leave a mango behind)

Lastly, he will have to travel the rest of 167 miles with the remaining 1000 mangoes and by the time he reaches town, he will be left with 833 mangoes.

43

If you analyze, then you will find that all the 6 numbers divisible by 3 can be ordered. Why? Because you can break them own as the sum of 6 and 9.
Now after 26, all the numbers that are divisible by 3 if subtracted by 40 can be obtained.
After 46, all the numbers will fit into one of the above categories and thus all such numbers can be obtained. But 43 will be last number that will not fall into one of the above categories.
44 = 20 + 6 * 4, 45 = 6 * 6 + 9

Product is 52 and sum is 17. The numbers are 4 and 13.

The correct answers are b, a, True, False and False. Also, the scores are Justin (0), Adam (1), Cabe (2), Vince (3) and Michael (4).

Since no two students were able to answer the exact number of correct answers, there can be only two possibilities
1) 1 + 2 +3 + 4 + 5 = 15
2) 0 + 1 + 2 + 3 + 4 = 10

Now let us determine the maximum number of correct answers possible through the answers they gave.
For Question I = 2 (b or c)
For Question II = 2 (b or c)
For Question III = 4 (True)
For Question IV = 4 (True)
For Question V = 3 (True)

Now we know that the maximum number of correct answers possible are 15 (2+2+4+4+3) according to which, Adam would have given all correct answers as only he answered True for questions III, IV and V. But then Cabe and Justin would have given exactly 3 correct answers. And also, Michael and Vince would have given 2 correct answers. Therefore none of them got all the five correct answers. Thus this assumption is wrong.

The total number of correct answers therefore are 10 (0+1+2+3+4). Both Questions III and IV cannot be False as in that case, the number of correct answers would not be 10. So the student who got all wrong answers cannot be Cabe, Adam and Michael.

Suppose if Vince got all wrong, then Cabe, Justin and Michael each would have at least 2 correct answers. Thus, Adam would have to be the student with only one correct answer and in that case, the correct answers for questions I and II would be a and a respectively. But that is not possible as then the total number of correct answers would be 1 (a) + 1 (a) + 1 (False) + 4 (True) + 2 (Flase) = 9.

Thus it is Justin who has given all wrong answers. The correct answers are b, a, True, False and False. Also, the scores are Justin (0), Adam (1), Cabe (2), Vince (3) and Michael (4).

1. Fireman and the fit guy will move first which will take 2 minutes.
2. Fireman will return back with fire extinguisher, taking 1 minutes.
3. Drunk guy will move with old woman taking 5 minutes.
4. The fit guy will return taking 2 minutes.
5. Both the fit guy and fireman will move taking 2 minutes.

2 + 1 + 5 + 2 + 2 = 12 minutes.

The answer is 9^(9-9)