Question 7
Three pipes A, B and C can fill the cistern in 12 hours, 20 hours and 15 hours respectively. If A is operated for all the time and pipe B and C are opened alternately which B being first. Find the time taken to fill the cistern.
**Editorial input format:** Explain the missing switching condition and give a correctly justified result under an explicitly stated schedule. This source omission requires manual grading.
**Editorial input format:** Explain the missing switching condition and give a correctly justified result under an explicitly stated schedule. This source omission requires manual grading.