Why Aeroplane windows are round?

You are given four results as below:
1111 = F
2222 = E
3333 = T
Then, can you find out how to code 4444?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

Spot the cat in the picture below

A beggar on the street can make one cigarette out of every 6 cigarette butts he finds. After one whole day of searching and checking public ashtrays the beggar finds a total of 72 cigarette butts. How many cigarettes can he make and smoke from the butts he found?

Rose, Lily and Jasmine decided to buy flowers for their moms on Mother's Day. One of them bought lilies, the other roses, and the third one jasmines.
'It's funny!' said the girl with roses, 'we bought roses, jasmines and lilies, but none of us bought the flowers matching her name'.
'You're right!', said Lily.
What kind of flowers did each of the girls buy?

On rolling two dices (six-sided normal dice) together, what is the probability that the first one comes up with a 2 and the second one comes up with a 5?

How could a baby fall out of a twenty-story building onto the ground and live?

Which number should replace the question mark?

Two girls were born to the same mother, on the same day, at the same time, in the same month and year and yet they're not twins. How can this be ?