Can you replace the question mark with the correct number?

Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

You stand in front of two doors. A guard stands next to each door. You know the following things: one path leads to paradise, the other leads to death. You cannot distinguish between the two doors. You also know that one of the two guards always tells the truth and the other always lies. You have permission to ask one guard one question to discover which door leads to paradise. What one question would you ask to guarantee you enter the door to paradise?

In a concert, Christina is performing a dance show with her group.
At 10:00, she and her crew were dancing in an absolutely straight line. At that time Christina was standing in 4th position from both the front and back end of the row.

What was the size of her crew?

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

Find the next number in the series below

21 32 54 87 131 ?

If eleven plus two equals one, what does nine plus five equal?

Five teams were competing in cricket where they faced each other exactly once. After the tournament, the following is the point table.

DareDevils 6
SuperKings 5
Royals 4
Sunrisers 2
Riders ?

How many points did Riders end up with?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

Can you place three balls such that the equation shown in the picture holds true?