Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

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?

Sally lives in a place where six months of the year is mild summer and the temperature drops significantly the other six months. She owns a lake where there is a small island. She wants to build a house on the island and needs to get materials there. She doesn’t have a boat, plane, or anything to transport them to the island. How does Sally solve this problem?

John is the son of Jacob.
So,
Jacob is the_____of John's father?

How many triangles are there on the puzzle below?

What has many teeth, but cannot bite?

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

I have two coins.
* One of the coins is a faulty coin having a tail on both sides of it.
* The other coin is a perfect coin (heads on side and tail on other).

I blindfold myself and pick a coin and put the coin on the table. The face of the coin towards the sky is the tail.

What is the probability that another side is also tail?