Solution:

7 minutes hourglass = p
11 minutes hourglass = q

Turn p and q.
P will finish at 7 minutes and then turn it again.
When q finishes (11 minutes), turn p again.
It will take 4 minutes for p to become empty.

The total time if you count is 15 minutes when p empties.

Solution:

Give Up

SLOW when read down gives us Slow Down.
GIVE when read upwards gives us Give Up.

Solution:

It is not Richard because if it was, Richard 1 and Morgan 3 would both be false, which would make Richard 2 and Morgan 2 both true which is a contradiction.

It is not Travis because if it was, Travis 1 and Travis 3 would both be false, which is not possible.

Therefore, the killer must be Morgan.

Solution:

The missing number is 399.

Explanation:
84 = 4^3 + 3^2 + 4
155 = 5^3 + 5^2 + 5
258 = 6^3 + 6^2 + 6
584 = 8^3 + 8^2 + 8
819 = 9^3 + 9^2 + 9

Thus,
399 = 7^3 + 7^2 + 7

Solution:

Cousins

Explanation:
Parent of Beta is Alpha.
Parent of Zeta is Epsilon.
Parent of Delta is Gamma.

Ergo, Epsilon is Alpha's brother and Gamma is Alpha's sister.

Therefore, Zeta, Beta and Delta are cousins.

Solution:

Actutally, the name of that boy is "Shut Up," and he is playing hide-and-seek with two of his friends who are named "Manners" and "Trouble". "Trouble" is the one who counted and he is looking for the other two boys. "Manners" is hiding up in the tree.

Solution:

I am trouble.

Solution:

Yes, you should switch the envelope. In the beginning when you picked up the envelope, you had a 1/3 probability of finding an offer letter in the envelope. There was 2/3 chance that the letter was there in the two envelopes on the table.

If you keep your selected envelope, you still have a 1/3 chance of finding an offer letter in that. However, since the interviewer has removed one empty envelope from the table, if you switch, you have a probability of 2/3 that the offer letter is inside that.

Solution:

Yes. You can do it by selling them.

Solution:

The word is Energy.
Nobody said anything about the order of 'g', 'r' and 'y' at the end of the word.
Also, we use energy every day.

Solution:

There are 56 triangles add up to in the Snowflake plan.

There are 5 in the big equilateral triangle part into littler equilateral triangles.

There are 3 inside the focal little equilateral triangle utilizing the core vertex.

There are 18 (3 * 6) with the additional hexagonal sides around the little equilateral triangle.

There are 30 (3 * 10) with the additional hexagonal sides around the huge equilateral triangle.

Solution:

The man said, 'I will be killed by giving poison.'

If Akbar says the statement is true, the man will be killed by hanging which will make his statement false.
If Akbar says the statement is false, the man will be killed by giving poison which will make the statement true.

Thus Akbar had no choice but to leave the man unpunished.

Solution:

Mayank took birth on Sunday.

Mayank was born 25 days before Rohit and thus the birth date of Mayank will be 8 Feb 1970.
Republic Day fell on Monday.
Number of days if counted from 26 January to 8 February will be 13.

After 13 days of Monday, it will be Sunday.

Solution:

Let the cost of cap = m
Cost of pen = (5 + m)

As per the condition

5.50 = 5 + m + m
2m = 0.5
m = 0.25

Hence, the cap costs 25 Paise.

Solution:

Stand up comedy (stand up comma D)

Solution:

Birbal wrote - "This time will pass soon."

When read in good time, you will feel sad. However, it is essential to keep the fact in the mind. Thus, do not be haughty and keep doing the good work for society.

When read in bad time, you will feel optimistic and get a morale boost that with your hard work you can change the situation.

Solution:

23

Explanation:
If you interchange the digits in the squares, you will see that all the resulting numbers are square of some number. Now square root all the thus formed numbers and add them together and you will have the required number in the circle.

In the third figure:
61 = 16 and square root = 4
90 = 09 and square root = 3
18 = 81 and square root = 9
94 = 49 and square root = 7

4 + 3 + 9 + 7 = 23.

Solution:

This is because the contestants had to hold their breath.

Solution:

Mixing business with pleasure.(PbLuEsAiSnUeRsEs)

Solution:

28 is the required number.

28 * 3 - 2 = 82.