Before Mount Everest was discovered, what was the highest mountain in the world?

What is the next number in the series?

15 29 56 108 208 ?

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 ?

Can you count the number of triangles in the given picture?

Solve the rebus riddle in the picture below.

There are two beautiful yet remote islands in the South Pacific. The Islanders born on one island always tell the truth, and the Islanders from the other island always lie.
You are on one of the islands and meet three Islanders. You ask the first which island they are from in the most appropriate Polynesian tongue, and he indicates that the other two Islanders are from the same island. You ask the second Islander the same question, and he also indicates that the other two Islanders are from the same island.
Can you guess what the third Islander will answer to the same question?

In which direction should the missing arrow point?

Why is a river so rich ?

Can you write down eight eights so that they add up to one thousand?

Can you count the number of matches in the picture below ?