Solution:

9

1(Mr. Beckham) + 1(Mrs. Beckham) + 6 (daughters) + 1 (brother).

Solution:

Frank was born in room #1933

Solution:

The blazer from man3 is on the boss's chair. So he is the boss.

Solution:

The man is dead and not mute.

Solution:

The Letter L

Solution:

In a clock.

Explanation:
1300 + 20 = 1:00PM + 20 minutes = 1:20 PM

1400 - 40 = 2:00PM - 40 minutes = 1:20 PM

Solution:

C

Explanation:
It Seems, the water level might be even in all the glasses, but what will happened if we remove the objects from the glasses. When you put an object in water, it will displace the water with the mass of the object Hence, the glass that contains the object with the least amount of weight will have the most water in it.

Even though we might not know the exact weight of all those four objects, we can all agree, that the paper clip weighs the least and hence will displace the minimum water.

Solution:

The prisoner picks a marble and without showing it to anyone swallows it and then picks the remaining marble and shows to everyone which was black which proved the first marble prisoner pick must be white.
The Mad King has no option but to let the prisoner go.

Solution:

6

Explanation:
Key1: 3 attempts for 3 gates.
Key2: 2 attempts for remaining 2 gates.
Key3: 1 attempts for the last gate.

Solution:

Cup-8

Explanation:
This might be tricky for mobile users where the bottom cup is difficult to focus on.