What is 3/7 chicken, 2/3 cat and 2/4 goat?

What's the only room from which no one can enter or leave

Cristina leaves home and then she makes exactly 3 left turns and returns home where she found 2 girls wearing the mask.

Who are these two masked girls?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

Solve the following series:
AZ, GT, MN, __, YB

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it. The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it. The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?

Baseball bat and ball cost $100. If the bat cost $99 more than the ball, what is the cost of each?

A brand new Mobile Phone was on sale at 20% as a promotional offer. By what per cent must the Mobile price be increased to sell it at the original price again?

How do you go from 98 to 720 using just one letter?