Three workers can do a job in 6 days. Two of the workers work twice as fast as the third. How long would it take one of the faster workers to do the job himself?
A
15 days
B
18 days
C
24 days
D
12 days
উত্তরের বিবরণ
Question: Three workers can do a job in 6 days. Two of the workers work twice as fast as the third. How long would it take one of the faster workers to do the job himself?
Solution:
Let,
the first and 2nd worker need x days.
Third worker needs 2x days
ATQ,
(1/x) + (1/x) + (1/2x) = 1/6
⇒ (2 + 2 + 1)/2x = 1/6
⇒ 5/2x = 1/6
⇒ 2x = 30
∴ x = 15
So the one faster worker alone will take 15 days to complete the job.
0
Updated: 2 weeks 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 week 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 week ago
If P and Q together can complete a piece of work in 16 days and P alone in 24 days, in how many days can Q alone complete the work?
Created: 2 weeks ago
A
72 days
B
48 days
C
42 days
D
36 days
Question: If P and Q together can complete a piece of work in 16 days and P alone in 24 days, in how many days can Q alone complete the work?
Solution:
P and Q complete a work in = 16 days
One day's work of (P + Q) = 1/16
P complete the work in = 24 days;
One day's work of P = 1/24
Then, Q's one day's work = (1/16) - (1/24)
= (3 - 2)/48
= 1/48
So, Q alone can complete the work in = 48 days.
0
Updated: 2 weeks 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
