Replace the question mark with the correct number in the below-given picture?

My cousin lives in one story house in Antarctica. His house is made the of-of sandstone. what is the color of stairs?

Complete the following series. It.s very logical:

1, 4, 5, 6, 7, 9, 11, __?

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

John speaks the truth only once a day in a week. Below are a few hints for you:

First: Days are Sunday, Monday and so on.
Second: One day he says, "I lie on Monday and Tuesday".
Third: On the next day, he says, "Today is either Thursday, Saturday or Sunday".
Fourth: On the next day, he says, "I lie on Wednesday and Friday".

Can you identify the day on which he speaks the truth?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?

For an extra income, John decided to work at a Hotel for one hour daily. The manager offers him that they will pay him $11 after every 11 days.
However, John offered a different proposition to the manager. The offers stand as:
He will be paid just a penny on his first day.
Two pence will be paid on the second day,
Four pence will be paid on the third day.
And so on till the 11th day.

Should the Hotel manager accept his offer?

2 ladies and 2 girls need to cross a river in a boat big enough for 1 LADY or 2 girls. How do they do it?