Hasan can paint 54 walls in 27 minutes. Rafiq can paint 25 walls in 10 minutes. Working together, how many walls can they paint in 20 minutes?
A
60 walls
B
70 walls
C
90 walls
D
100 walls
উত্তরের বিবরণ
Question: Hasan can paint 54 walls in 27 minutes. Rafiq can paint 25 walls in 10 minutes. Working together, how many walls can they paint in 20 minutes?
Solution:
Hasan can paint in 1 minute = 54 ÷ 27 = 2 walls
Rafiq can paint in 1 minute = 25 ÷ 10 = 25/10 = 5/2 walls
∴ Together they can paint in 1 minute = 2 + (5/2) walls
= (4 + 5)/2 = 9/2 walls
∴ In 20 minutes, they can paint = (9/2) × 20 walls
= (9 × 20)/2
= 90 walls
0
Updated: 1 month ago
Machine A paints y units in 15 minutes and machine B paints 3y units in 30 minutes. In how many minutes will A and B, working together, paint 45y units?
Created: 1 month ago
A
270 minutes
B
240 minutes
C
250 minutes
D
280 minutes
Question: Machine A paints y units in 15 minutes and machine B paints 3y units in 30 minutes. In how many minutes will A and B, working together, paint 45y units?
Solution:
Machine A paints per minute = y/15 units
Machine B paints per minute = 3y/30 = y/10 units
∴ A and B together paint per minute = y/15 + y/10
= (2y + 3y)/30
= 5y/30
= y/6 units
So, to paint y/6 units, it takes 1 minute.
Hence, to paint 45y units, time needed = (45y × 6)/y = 270 minutes.
0
Updated: 1 month ago
Two pipes, A and B, can fill a tank in 37.5 minutes and 45 minutes. If both pipes are open, after how many minutes should pipe B be closed to fill the tank in half an hour?
Created: 3 weeks ago
A
5 minutes
B
9 minutes
C
10 minutes
D
15 minutes
Question: Two pipes, A and B, can fill a tank in 37.5 minutes and 45 minutes. If both pipes are open, after how many minutes should pipe B be closed to fill the tank in half an hour?
Solution:
নল A দ্বারা 37.5 মিনিটে পূর্ণ হয় 1 অংশ
∴ 1 মিনিটে পূর্ণ হয় = (1/37.5) অংশ
∴ 30 মিনিটে পূর্ণ হয় = 30/37.5 = 300/375 = 4/5 অংশ
∴ পূর্ণ হওয়ার বাকি থাকে = 1 - (4/5)
= (5 - 4)/5
= 1/5 অংশ
B নল দ্বারা ,
1 অংশ পূর্ণ হতে সময় লাগে = 45 মিনিট
∴ 1/5 অংশ পূর্ণ হতে সময় লাগে = 45 × (1/5) = 9 মিনিট
∴ B নলটি 9 মিনিট পর বন্ধ করলে ট্যাংকটি 30 মিনিটে পূর্ণ হবে।
Shortcut:
(30/37.5) + (x/45) = 1 (whole)
⇒ 0.8 + (x/45) = 1
⇒ x/45 = 1 - 0.8 = 0.2
⇒ x = 0.2 × 45 = 9
0
Updated: 3 weeks ago
A ferry can carry 30 trucks or 50 motorcycles at a time. If there are 18 trucks on the ferry, how many motorcycles can be loaded onto it?
Created: 1 month ago
A
20
B
24
C
16
D
30
Question: A ferry can carry 30 trucks or 50 motorcycles at a time. If there are 18 trucks on the ferry, how many motorcycles can be loaded onto it?
Explanation:
Given,
30 trucks = 50 motorcycles
∴ 1 truck = 50/30 = 5/3 motorcycles
∴ 18 trucks = 18 × 5/3 = 30 motorcycles
Maximum motorcycles on ferry = 50
∴ Remaining motorcycles that can be loaded = 50 - 30 = 20
So, the ferry can carry 20 more motorcycles along with the 18 trucks.
0
Updated: 1 month ago
