Rafi and Shafi can paint a room in 4 days. Shafi can do it alone in 6 days. How many days will Rafi take to paint the room alone?
A
12 days
B
10 days
C
15 days
D
9 days
উত্তরের বিবরণ
Question: Rafi and Shafi can paint a room in 4 days. Shafi can do it alone in 6 days. How many days will Rafi take to paint the room alone?
Solution:
ধরা যাক,
Rafi একা কাজটি করতে x দিন সময় নেন।
∴ Rafi-র 1 দিনের কাজ = 1/x
∴ Shafi-র 1 দিনের কাজ = 1/6 (কারণ সে একা ৬ দিনে কাজটি করে)
তারা দুজনে মিলে ৪ দিনে কাজ শেষ করে।
∴ তাদের 1 দিনের একত্রে কাজ = 1/4
এখন,
(1/x) + (1/6) = 1/4
⇒ (6 + x) / (6x) = 1/4
⇒ 4(6 + x) = 6x
⇒ 24 + 4x = 6x
⇒ 24 = 6x - 4x = 2x
⇒ x = 24 / 2 = 12
∴ Rafi একা কাজটি করতে 12 দিন সময় নেবে।
0
Updated: 1 month ago
If Rafi and Suman together can complete a job in 12 days. If Rafi alone can finish the job in 20 days, in how many days can Suman alone complete the work?
Created: 2 months ago
A
25 days
B
60 days
C
45 days
D
30 days
Question: If Rafi and Suman together can complete a job in 12 days. If Rafi alone can finish the job in 20 days, in how many days can Suman alone complete the work?
Solution:
Rafi and Suman together can complete a piece of work in 12 days
Rafi and Suman together can complete in 1 day = 1/12
Rafi alone in 20 days
Rafi alone in one day = 1/20
∴ Suman complete in one day = (1/12) - (1/20)
= (5 - 3)/60
= 2/60
= 1/30
∴ Suman can complete the work in 30 days
0
Updated: 2 months ago
X can do a work in 10 days and Y in 15 days. If they work on it together for 3 days, then the fraction of the work that is left is-
Created: 2 months ago
A
1/3 part
B
1/2 part
C
3/4 part
D
1/4 part
Question: X can do a work in 10 days and Y in 15 days. If they work on it together for 3 days, then the fraction of the work that is left is-
Solution:
X's 1 day's work = 1/10
Y's 1 day's work = 1/15
∴ (X + Y)'s 1 day's work = (1/10) + (1/15) part
= (3 + 2)/30 part
= 5/30
= 1/6 part
∴ (X + Y)'s 3 day's work = (1/6) × 3) part
= 1/2 part
Therefore, Remaining work = 1 - (1/2) = 1/2 part
0
Updated: 2 months ago
A worker earns Tk. 300 on the first day and spends Tk. 150 on the second day, earns Tk. 300 on the third day and again spends Tk. 150 on the fourth day, and so on. On which day would he have had Tk. 1500?
Created: 1 month ago
A
16th day
B
17th day
C
19th day
D
21st day
Question: A worker earns Tk. 300 on the first day and spends Tk. 150 on the second day, earns Tk. 300 on the third day and again spends Tk. 150 on the fourth day, and so on. On which day would he have had Tk. 1500?
Solution:
1ম দিনে আয় = 300 টাকা
2য় দিনে ব্যয় = 150 টাকা
∴ প্রতি 2 দিনে জমা হয় = 300 - 150 = 150 টাকা
শুধু 1ম দিনে আয় করায় হাতে থাকে = 300 টাকা
অতএব, 1500 - 300 = 1200 টাকা আরও জমা করতে হবে।
150 টাকা জমা হয় 2 দিনে,
∴ 1200 টাকা জমা হয় = (2 × 1200)/150 = 16 দিনে
অর্থাৎ, 16 দিনের শেষে জমা থাকবে = 1200 টাকা
17-তম দিনে আবার আয় হবে = 300 টাকা
∴ মোট সঞ্চয় হবে = 1200 + 300 = 1500 টাকা
∴ 17-তম দিনে তার কাছে মোট 1500 টাকা জমা থাকবে।
0
Updated: 1 month ago
