If each observation of the data is decreased by 15; then the mean :

1. remains same

2. is increased by 15

3. is decreased by 15

4. is multiplied by 15

If the mean of x₁ and x₂ is 12.5 and mean of x₁, x₂ and x₃ is 16. The value of x₃ is :

1. 32

2. 3.5

3. 285

4. 23

Find the mean of first six natural numbers.

Find the mean of first ten odd natural numbers.