Solution:

Colors:
Y B R G
G R B Y
B Y G R
R G Y B


Signs:
x + - /
- / x +
/ - + x
+ x / -

Solution:

XIX is the answer which refers to nineteen in roman numeric system. On taking out one i.e. I, we will get XX that is equal to twenty.

Solution:

I + IX = X

The equation read from the other side becomes X = XI + I which is false.

Solution:

C

VIII has taken place of VII.

Solution:

fIvE thOUsAnd(5000)

Solution:

When you were inside the shed, the murderer replaced the lock with his own one that was identical to your original lock. When you locked the store room, you did not require a key and there was nothing abnormal for you. When you left, the murderer opened the lock with his key, planted the dead body inside and replaced the lock again putting the original lock in the place. He then closed it without any problem.

Solution:

A parachute

Solution:

6380

2*2-1 3*3-1 =>38
4*4-1 5*5-1 =>1524 and so on

Solution:

She simply asked everyone to raise hands on hearing the question. The only condition was that the ones who knew the correct answer will raise right hand and other will raise left hand facilitating her in acknowledging the ones to pick for answering.

Solution:

Amelia --> vanilla-shake
Charlotte --> chocolate-shake
Evelyn --> strawberry-shake
Anna --> burger
Ella --> curd