A water tank has two taps (Tap-1 and Tap-2): Tap-1 can fill a tank in 8 hours and Tap- 2 can empty the tank in 16 hours. How long will they take to fill the tank if both taps are opened simultaneously but Tap-2 is closed after 8 hours?
বিকল্পসমূহ (নিজের উত্তর যাচাই করতে ক্লিক করুন):
সঠিক উত্তর
1 (12)
বিস্তারিত ব্যাখ্যা ও বিশ্লেষণ:
Solution:
Tap-1, in 8 hrs fills = 1 portion
So, in 1 hr it fills = 1/8 portion
Tap-2, in 16 hrs empties = 1 portion
So, in 1 hr it empties = 1/16 portion
When both taps are open, in 8 hrs it fills = 1 - 1/2 = 1/2 portion
Remaining = 1 - 1/2 = 1/2
As Tap-2 is closed after 8 hrs
Remaining 1/2 will be filled by Tap-1 in = 8 × 1/2 = 4 hrs
∴ Total time required = 8 + 4 = 12 hrs
