'A' can do a work in 10 days, and 'B' in 15 days. They work together for 4 days. How much of the work is left?
A
1/3
B
1/4
C
1/2
D
3/8
উত্তরের বিবরণ
Question: 'A' can do a work in 10 days, and 'B' in 15 days. They work together for 4 days. How much of the work is left?
Solution:
মনে করি,
সম্পূর্ণ কাজ = 1 অংশ
∴ A একা একদিনে করে = 1/10 অংশ।
B একা একদিনে করে = 1/15 অংশ।
∴ A ও B একসাথে একদিনে করে = (1/10) + (1/15) অংশ
= (3 + 2)/30
= 5/30
= 1/6 অংশ
∴ A ও B একসাথে 4 দিনে করে = 4 × (1/6) অংশ
= 2/3 অংশ
∴ কাজ বাকি থাকে = 1 - (2/3) অংশ
= (3 - 2)/3
= 1/3 অংশ
0
Updated: 1 week ago
If 5 workers can paint a house in 8 hours, how long would it take 20 workers to paint the same house?
Created: 1 week ago
A
2 hours
B
3 hours
C
5 hours
D
1 hours
Question: If 5 workers can paint a house in 8 hours, how long would it take 20 workers to paint the same house?
Solution:
5 workers can paint a house in 8 hours
∴ 1 worker would take = (8 × 5) hours
∴ 20 workers would take = (8 × 5)/20 hours
= 2 hours
0
Updated: 1 week ago
Three mechanics A, B, and C can manufacture 120 units in 12, 20, and 30 hours respectively. What is the ratio of the time taken by A alone to complete the work to the time taken by all three working together to complete the same work?
Created: 2 weeks ago
A
5 : 2
B
4 : 3
C
3 : 1
D
2 : 1
Question: Three mechanics A, B, and C can manufacture 120 units in 12, 20, and 30 hours respectively. What is the ratio of the time taken by A alone to complete the work to the time taken by all three working together to complete the same work?
Solution:
(A + B + C) together can do in 1 hour = (1/12) + (1/20) + (1/30)
= (5 + 3 + 2)/60
= 10/60
= 1/6
So, working together they complete the work in 6 hours.
And A alone takes 12 hours.
∴ Ratio of the time taken by A and (A + B + C) =12 : 6 = 2 : 1
0
Updated: 2 weeks ago
If A and B can complete a work together in 10 days, B and C together in 15 days, and A and C together in 12 days, then in how many days can B alone complete the work?
Created: 1 week ago
A
24 days
B
48 days
C
54 days
D
36 days
Question: If A and B can complete a work together in 10 days, B and C together in 15 days, and A and C together in 12 days, then in how many days can B alone complete the work?
Solution:
মনে করি,
সম্পূর্ণ কাজ = 1 অংশ
∴ (A + B) একদিনে করে = 1/10 অংশ। ..........(1)
(B + C) একদিনে করে = 1/15 অংশ। ..........(2)
(A + C) একদিনে করে = 1/12 অংশ। ..........(3)
(1), (2), (3) যোগ করে পাই,
2 × (A + B + C) = (1/10) + (1/15) + (1/12)
⇒ 2 × (A + B + C) = (6 + 4 + 5)/60 = 15/60
⇒ 2 × (A + B + C) = 1/4
⇒ (A + B + C) = 1/8
∴ A, B এবং C একসাথে একদিনে করে = 1/8 অংশ।
(A + B + C) একসাথে একদিনে করে 1/8 অংশ।
(A + C) একসাথে একদিনে করে 1/12 অংশ।
∴ B-এর একদিনের কাজ = 1/8 - 1/12
= (3 - 2)/24
= 1/24
অর্থাৎ,
B সম্পূর্ণ কাজ করে = (1 ÷ 1/24) = 24 দিনে
0
Updated: 1 week ago
