C and D together can complete a task in 6 days. C alone can do it in 10 days. How many days would it take D to do this job alone?
A
10
B
15
C
12
D
18
উত্তরের বিবরণ
Question: C and D together can complete a task in 6 days. C alone can do it in 10 days. How many days would it take D to do this job alone?
Solution:
C একা ১০ দিনে কাজটি করতে পারে।
∴ C এর একদিনের কাজ = 1/10
C ও D একসাথে ৬ দিনে কাজটি শেষ করে।
∴ তাদের একদিনের সম্মিলিত কাজ = 1/6
তাহলে, D এর একদিনের কাজ = 1/6 - 1/10
= (10 - 6)/60
= 4/60
= 1/15
অর্থাৎ, D এক দিনে কাজ করে 1/15 অংশ।
∴ পুরো কাজ শেষ করতে D এর সময় = 1 ÷ (1/15) = 15 দিন
0
Updated: 1 week ago
Rafi alone can complete a work in 10 days and Tareq alone can complete it in 15 days. Rafi and Tareq undertook to complete the work for Tk. 7500. With the help of Salman, they finished the work in 5 days. How much should Salman be paid?
Created: 1 week ago
A
Tk. 1200
B
Tk. 1250
C
Tk. 1300
D
Tk. 1380
Question: Rafi alone can complete a work in 10 days and Tareq alone can complete it in 15 days. Rafi and Tareq undertook to complete the work for Tk. 7500. With the help of Salman, they finished the work in 5 days. How much should Salman be paid?
Solution:
Rafi's 1 day work = 1/10
Tareq's 1 day work = 1/15
Rafi + Tareq + Salman's 1 day work = 1/5
∴ Salman's 1 day work = 1/5 - (1/10 + 1/15)
= (6 - 3 - 2)/30
= 1/30
Salman's 5 days work = 5 × 1/30 = 1/6
Salman completed 1/6 of the total work.
∴ He should be paid 1/6 of Tk. 7500
∴ Salman’s payment = 7500 × 1/6 = Tk. 1250
0
Updated: 1 week ago
30 workers can build 60 machines working 4 hours per day. How many extra workers are required to produce 90 machines working 6 hours per day?
Created: 2 weeks ago
A
0 workers
B
10 workers
C
20 workers
D
15 workers
Question: 30 workers can build 60 machines working 4 hours per day. How many extra workers are required to produce 90 machines working 6 hours per day?
Solution:
4 hours to build 60 machines by 30 workers
1 hour to build 1 machine by = (30 × 4)/60 workers
6 hours to build 90 machines by = (2 × 90)/6 workers
= 30 workers
∴ extra workers = (30 - 30) = 0 workers
0
Updated: 2 weeks ago
A can complete a work in 20 days, B in 30 days, and C in 60 days. A stops working 4 days before the completion of the work, and B stops 6 days before completion. C continues working alone till the end. What was the total number of days taken to complete the entire work?
Created: 1 week ago
A
10 days
B
14 days
C
18 days
D
21 days
Question: A can complete a work in 20 days, B in 30 days, and C in 60 days. A stops working 4 days before the completion of the work, and B stops 6 days before completion. C continues working alone till the end. What was the total number of days taken to complete the entire work?
Solution:
Let the total work be completed in y days.
∴ A worked for (y - 4) days
So his contribution = (y - 4)/20
B worked for (y - 6) days
So his contribution = (y - 6)/30
C worked full y days, so his contribution = y/60
Therefore,
(y - 4)/20 + (y - 6)/30 + y/60 = 1
⇒ 3(y - 4) + 2(y - 6) + y = 60
⇒ 3y - 12 + 2y - 12 + y = 60
⇒ 6y - 24 = 60
⇒ 6y = 84
⇒ y = 14
∴ The total work was completed in 14 days.
0
Updated: 1 week ago
