Situations where a medical doctor would recommend injection of pre-formed antibodies (antitoxins):
1. Tetanus infection:
- A doctor may recommend the injection of tetanus antitoxin when a person is injured with a contaminated object or is exposed to tetanus-causing bacteria. Since the body has not yet produced antibodies to the toxin, the immediate administration of pre-formed antibodies can neutralize the tetanus toxin and prevent infection.
2. Snakebite (venom):
- If a person is bitten by a venomous snake, the doctor may administer snake antivenom (which contains pre-formed antibodies against the snake's venom). This is done to neutralize the venom before it can spread and cause severe harm to the body.

A ladder of fixed length \( h \) is to be placed along the wall such that it is free to move along the height of the wall.
Based upon the above information, answer the following questions:
(iii) (b) If the foot of the ladder, whose length is 5 m, is being pulled towards the wall such that the rate of decrease of distance \( y \) is \( 2 \, \text{m/s} \), then at what rate is the height on the wall \( x \) increasing when the foot of the ladder is 3 m away from the wall?