A man can do a work in 20 days and a woman in 15 days. If they work on it together for 5 days, then the fraction of the work that is left-
A
8/15
B
1/12
C
5/12
D
None of these
উত্তরের বিবরণ
Question: A man can do a work in 20 days and a woman in 15 days. If they work on it together for 5 days, then the fraction of the work that is left-
Solution:
Man's 1 day's work = 1/20
Woman's 1 day's work = 1/15
∴ (Man + woman)'s 1 day's work = (1/20) + (1/15) = (3 + 4)/60 = 7/60
∴ (Man + woman)'s 5 day's work = (7/60) × 5 = 7/12
Thus, Remaining work = 1 - (7/12) = (12 - 7)/12 = 5/12
∴ The fraction of the work that is left = 5/12
0
Updated: 2 months ago
If 10 men or 18 women can do a work in 50 days then how many days would it take 25 men and 15 women to do twice the work?
Created: 2 months ago
A
25 days
B
30 days
C
32 days
D
40 days
Question: If 10 men or 18 women can do a work in 50 days then how many days would it take 25 men and 15 women to do twice the work?
Solution:
Here,
10 men = 18 women
∴ 1 men = 18/10 women
∴ 25 men = (18 × 25)/10 women
= 45 women
∴ 25 men and 15 women = (45 + 15) = 60 women
ATQ,
18 women can do the work in 50 days
∴ 1 women can do the work in = (50 × 18) days
∴ 60 women can do the work in (50 × 18)/60 days
= 15 days
Hence to do twice the work time need = (15 × 2) = 30 days
0
Updated: 2 months 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 months 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 months 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 months 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 months ago
