বিগত সালের প্রশ্ন ও প্রশ্ন ব্যাংক
বিসিএস, ব্যাংক, প্রাথমিক শিক্ষক ও সকল সরকারি চাকরির বিগত সালের প্রশ্ন ও অধ্যায়ভিত্তিক নির্ভুল সমাধান
Solution:
Here,
B's 1 day's work = 1/20 part
C's 1 day's work = 1/30 part
∴ (B + C)'s 1 day's work = (1/20 + 1/30) part
∴ (B+C)'s 2 day's work = {(1/20 + 1/30) × 2} part = [{(3+2)/60} × 2] part
= (5/60 × 2) part
= 1/6 part
Remaining work = (1 -1/6) part
= 5/6 part
A's one day's work = 1/18 part
∴ The time taken by A alone to complete the remaining work is = (5/6)/(1/18) days = 15 days
Solution:
Work done by B in 17 days = {(1/35) × 17} part
= 17/35 part
Remaining work = (1 - 17/35) part
= 18/35 part
(A + B)'s 1 day's work = (1/28 + 1/35) part
= 9/140 part
Now,
9/140 part work has done by (A + B) in 1 day
∴ 1 part work has done by (A + B) in 140/9 days
∴ 18/35 part work has done by (A + B) in = {(140/9) × (18/35)} days = 8 days
∴ A leave After 8 days
Solution:
A's 1 day's work = 1/24 part
A's 18 day's work = 18/24 part
= 3/4 part
Remaining work = 1 - 3/4 = 1/4 part
1/4 part work done by B in = (18 - 6) = 12 days
∴ 1 part work done by B in = (12 × 4) = 48 days
Solution:
Ratio of times taken by A and B = 100/80 = 5/4
Let B takes x days to do the work
ATQ,
5/4 = (15/2)/x
⇒ 5/4 = (15/2)/x
⇒ 5x = (15 × 4)/2
⇒ 5x = 30
∴ x = 6 hours