What question can you never answer yes to?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

You have $100 with you and you have to buy 100 balls with it. 100 is the exact figure and you can't go below or above the numbers and you have to use the entire $100. If there is no kind of tax applied how many of each of the following balls will you be able to buy:

Green Balls costing $6
Yellow Balls costing $3
Black Balls costing $0.10

Now, how many of each must you buy to fulfil the condition given?

The day after tomorrow will be three days before Tuesday. Can you find out what is today?

A mathematics teacher took exams for his students. Out of the total students, 25% passed both the tests included in the exam. However, only 42% were able to clear the first test.

Can you find out the percentage of those students who passed the first test and also passed the second test?

What number divided by 4 is the same as that number minus 4?

Create a number using only the digits 4,4,3,3,2,2,1 and 1. So i can only be eight digits. You have to make sure the ones are separated by one digit, the twos are separated by two digits the threes are separated with three digits and the fours are separated by four digits

There’s a girl who has a large family. She has an equal amount of brothers and sisters, but each brother only has half as many brothers and sisters. What’s the correct amount of brothers and sisters?