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?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

You are mixing a mixture of cement and Sand with five gallons of water. You have a garden hose giving you all the water you need. The problem is that you only have a four-gallon bucket and a seven-gallon bucket and neither has graduation marks. Find a method to measure five gallons.

I don't get anymore wetter, no matter how much rain falls on me.

What is more useful when it is broken?

Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT

John is asked to stand behind Jacob and Jacob is asked to stand behind John. Both of them feel confused about it and don't know what to do?

But it is quite possible, do you know how?

As you can see that fifteen matches have been used to form an arrangement. What you have to do is remove any six of them to make them ten.

I am a number I am not an odd number I am higher than 90 I am not higher than 100 If you subtract me from 100, you get nothing. What number am I?

In the Mexico City area, there are two Houses H1 and H2. Both H1 and H2 have two children each.
In House H1, The boy plays for Mexico Youth academy and the other child plays baseball.
In House H2, The boy Plays soccer for his school in Mexico and they recently have a newborn.

Can you prove that the probability of House-H1 having a girl child is more than that of House-H2?