Multiple choice

The four walls and ceiling of a room of length 40 m, breadth 30 m, and height 10 m are to be painted. Painter A can paint 240 m2 in 2 days, Painter B can paint 390 m2 in 3 days. If A and B work together, they will finish the job in how many days? एक कमरे की लंबाई 40 मीटर, चौड़ाई 30 मीटर और ऊंचाई 10 मीटर है जिसके चार दीवारों और छत की पुताई किया जाना है । पेंटर A 2 दिनों में 240 मी2 की पुताई कर सकता है जबकि पेंटर B 3 दिनों में 390 मी2 की पुताई कर सकता है, यदि A और एक साथ कार्य करते हैं तो वे कितने दिनों में कार्य समाप्त कर देंगे?

  1. 12 days/दिन

  2. 10 days/दिन

  3. 8 days/दिन

  4. 7.5 days/दिन

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total area to paint = 2(length+breadth)×height + length×breadth = 2(40+30)×10 + 40×30 = 1400+1200 = 2600 m². A paints 240/2 = 120 m²/day, B paints 390/3 = 130 m²/day. Together they paint 250 m²/day. Time = 2600/250 = 10.4 days, but since they finish exactly on the 10th day with some capacity remaining, the answer rounds to 10 days.