Question

it is much easier to burst on inflated balloon with a needle than by a finger

Answer 1

needle will have sharp ends which makes it easier to pierce the baloon its area is less so more pressure
and our finger is blund so it cannon pierce the baloon easily

Answer 2

the surface area of a needle's sharp pointed area is less but our finger tip has greater surface area when compared to the needle..when the surface area is small, the force per unit area (pressure) is great..so it is easy..(pls check this answer with others)