Why Aeroplane windows are round?

I want to fill my bucket using both cold and hot water.
I have two taps for both cold and hot water. The hot water tap fills the bucket in exact 6 hours and the cold water tap fills the bucket in exact 4 hours.
I turn both of them simultaneously but I forgot to turn off another tap which removes the water out of the bucket. This tap can empty the bucket in 12 hours.

How Long will it take to fill the bucket?

Teacher ask the student

'Why are you standing on that chair in music class ?'.

what did student replied ?

Check out the number list below and find what number comes next in the sequence.

111 , 113 , 117 , 119 , 123 , 137 , ?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

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

Can you spot what's wrong with the following sentence?

PETER WAS ANGRY AT
HIMSELF BECAUSE HE
ACCIDENTALLY LEFT THE
THE KEYS TO HIS CAR
AT HIS FRIEND'S HOUSE.

If Bihan is 10, Anirudha is 20, and Kim and Seal are both 5, but Rikold is 10, how much is Kenniger by the same trend?

What number comes next in the series?

5 15 5 18 5 24 14 20 _