Question

Quiet operation of a fan depends mostly upon the
A. motor balance.
B. balance of the blades.
C. weight of the blades.
D. material of the blades

Answer 1

The answers you seek are A and C

Answer 2

Answer:

B. balance of the blades.

Explanation:

If the all the blades of a fan do not have the same geometry and weight this leads to the imbalance of forces on the fan. Blade imbalance causes the improper spinning of the fan, this causes materials to rub against each other causing wear and tear and creating noise.

There are also other reasons why a fan might make noise but according to the options given here the balance of the blades is the best fit.