What four weights can be used to balance from 1 to 30 pounds?

What is the next number in this matchsticks series riddle?

I have some blue and red sock in my drawer. I have a total of 4 socks. I pick 2 socks and the chance that I get a pair of red socks is 1/2.

What is the chance of picking a pair of blue socks?

What number should come in place of the question mark below?

I have Rs.50 and I spend it in the way as below.

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

Count the number of squares in the picture below.