When 99 is considered higher than 100?

You want to boil a two-minute egg. If you only have a three-minute timer (hourglass), a four-minute timer and a five-minute timer, how can you boil the egg for only two minutes?

You have 10 balls with you. A friend of yours out of nowhere asks you to place those ten balls in five lines such that each of the lines has exactly 4 balls on them. He needs to check your intelligence. Prove him by doing the task.

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

I have Rs.50 and I spend it in the way as below.

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

What do you see in the image below

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

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

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?