What has many keys but can’t open a single lock?

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?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

In a fruit store, there was a unique weighing machine that was made to weigh only cherries and strawberries as they were priced the same.

Other fruits like watermelons or mango had different machines as they were expensive.

A man successfully buys watermelons at the price of cherries. How?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

While sitting in the Car, John suddenly finds that one of the wheels was missing. John noticed that a killer is approaching towards him. John cannot get out of the car.

How will John escape?

Which is faster, Heat or Cold ? Explain.

There is a box full of marbles,
all but two are blue,
all but two are green,
and all but two are red.

How many marbles are in the box?