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

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

Find 3 Differences Within This Excursion Scene In 20 Seconds

I have a big mouth and I am also quite loud! I am NOT a gossip but I do get involved with everyone's dirty business.

There are seven sisters in a house in a village where there is no electricity or any gadget.

Sister-1: Reading Novel
Sister-2: Cooking
Sister-3: Playing Chess
Sister-4: Playing Sudoku
Sister-5: Washing clothes
Sister-6: Gardening

what is Sister-7 doing ?

Move three sticks of the spiral below to form a square.

Find the number of squares in the below picture

How many times in a given day, minutes and hour clock comes in a straight line ?

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

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

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?