Solution:

prinka is 10, in a system that awards five for each vowel.

Solution:

An apple a day keeps the doctor away!

Solution:

Forest

Solution:

60.

100 years in a century, 365 days in a year, 24 hours in a day, 60 minutes in an hour, & 60 seconds in a minute.

Solution:

Silence

Solution:

It is not possible to guess only three fruits correctly: the fourth fruit is then correct too! So nobody has guessed three fruits correctly and 123-43-39-31 = 10 people have guessed four fruits correctly.

Solution:

Move the 6 up just a little bit.
2pow(6) -63 =1

Solution:

10 miles
Speed us 10miles/hour

Solution:

Name of a Person

Solution:

20
Just count the nines in the numbers: 6, 16, 26, 36, 46, 56, 76, 86, 96, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69.
Note: 66 contains TWO nines