What is the next number in this matchsticks series riddle?

I have two sand hourglasses:
1. A 7 minute one and
2. An 11-minute one.

Using just these 2 sand hourglasses, how can I measure time as 15 minutes?

What comes
Once in a Year
Twice in a Month
4 times in a Week
6 times in a Day

Can you decipher these quotes by Albert Einstein?
Blf xzm mvevi hloev z kilyovn lm gsv ovevo lm dsrxs rg dzh xivzgvw.

Imagine a box with two cogwheels, one big with 24 teeth and one small with 8 teeth. The big one is firmly attached to the center of the box which means it does not turn or move while the small one rotates around the big one.

How many times do you think that the smaller wheel will turn compared to the box when it turns once around the big one?

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 ?

How can a man go eight days without sleep?

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

The Judge knows that Alamgir was killed by his girlfriend Jasline, but the judge is unsure whether to punish her. Why?

What has lots of eyes, but can’t see?