If two's company, and three's a crowd, then whats four and five ?

what does the below rebus means?

You see a boat filled with people, yet there isn’t a single person on board. How is that possible?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

I am five letter word that is under you.
If you remove my 1st letter, then I am over you.
If you remove my 1st and 2nd letters then I am all around you.

Who am I?

Solve the following series:
AZ, GT, MN, __, YB

What is the last thing you take off before bed?

A 52% bias toss for head using the 51% tail bias coin was done to obtain a fair result.

Can you find how bias is the floor in this case?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

You have two bottles of pills marked with labels A and B. The pills are identical. The doctor has asked you to take one A pill and one B pill daily. You cant take more or less than that.

While taking out the pills one day, you took out one pill from A and by mistake took out two from B. You have no idea which pill is which now.

You cant throw away the expensive pills. What will you do now?