WBCS.LIVE practice question

It has to pay Rs. 225/- as bill when 9 bulbs are used for 30 days using them for 4 hours per day. Find the number of days if 5 bulbs are used for 6 hours per day for the payment of Rs. 375/- against the bill.

Solve this multiple-choice question and check the correct answer with its explanation below.

Answer options

  1. 60
  2. 55
  3. 50
  4. 45

Correct answer and explanation

Correct answer: 60

Explanation: āœ… Correct Answer: A. 60 šŸ“š Explanation: Total energy used is proportional to (number of bulbs multiplied by days multiplied by hours). Initial energy units are 9 * 30 * 4 = 1080, costing Rs 225. This means Rs 1 costs 4.8 units. For a bill of Rs 375, we need 375 * 4.8 = 1800 units. If we have 5 bulbs for 6 hours, the days required is 1800 divided by (5 * 6), which equals 60 days.