Directions(1-5):
Time and Work
1. A takes three times as long as B and C together to do a job. B takes four times as long as A and C together to do the same work, If all three, working together can complete the job in 24 days, then the number of days, A alone will take to finish the job is:
Answer: Option B
Explanation: Let 1 day's efficiency of each of the individuals is A, B and C respectively.
As per the given information, we get the efficiency equations as follows
3A = (B + C) ...(i)
A + B + C = 24 .....(ii)
Putting 3A in place of (B + C) in equation (ii), we get
A + 3A = 24
4A = 24
Now, 4A do the whole work in 24 days.
Therefore, A alone will do the whole work in 24 × 4 = 96 days
2. 4 boys and 3 women can do a piece of work in 6 days while 2 boys and 4 women can do the same piece of work in 9 days. How much time will be taken by 7 boys and 9 women to do the same piece of work?
A. 3 days
B. 7 days
C. 8 days
D. 12 days
Answer: Option A
Explanation: As per the given information, work done by 4 boys and 3 women in 6 days must be equal to work done by 2 boys and 4 women in 9 days.
Therefore, we get
(4B + 3W) × 6 = (2B + 4W) × 9
⇒ 24B + 18W = 18B + 36W
⇒ 6B = 18W ⇒ 1B = 3W
Now, 2B + 4W= (2 × 3)W + 4W = 10W
⇒ 10 women do a piece of work in 9 days.
Similarly, 7B + 9W = (7 × 3)w + 9W = 30W
Now, when 10 women do a piece of work in 9 days,
30 women (thrice of 10) will do the same piece of work in 3 days (∵ Time ∝ 1/Efficiency ).
3. Working alone, Typewriters A, B, C can do a certain typing job, consisting of a large number of pages, in 12, 15 and 18 hours, respectively. What is the ratio of the time it takes Typewriter A to do the job, working alone at its rate, to the time it takes Type writer B and C to do the job, working together at their individual rate?
A. [latex]\frac{4}{11}[/latex]
B. [latex]\frac{1}{2}[/latex]
C. [latex]\frac{15}{22}[/latex]
D. [latex]\frac{22}{15}[/latex]
Answer: Option D
Explanation: Since Typewriter B can do the job in 15 hours, it can do [latex]\frac{1}{15}[/latex] of the job in 1 hour.
Since Typewriter C can do the job in 18 hours
it can do [latex]\frac{1}{18}[/latex] of the job in 1 hour.
Together Typewriters B and C can do = ([latex]\frac{1}{15}[/latex] + [latex]\frac{1}{18}[/latex]) = [latex]\frac{6}{90}[/latex] + [latex]\frac{5}{90}[/latex] = [latex]\frac{11}{90}[/latex] of the job in 1 hour
Which means that it takes them = [latex]\frac{11}{90}[/latex] hours
to complete the job. Since Typewriter A completes the job in 12 hours, the ratio of the time required for A to do the job to the time required for B and C working together to do the job is
[latex]\frac{12}{\frac{90}{11}}[/latex] = [latex]\frac{12(90)}{11}[/latex] = [latex]\frac{2(11)}{15}[/latex] = [latex]\frac{22}{15}[/latex]
4. A, B and C can do a piece of work in 4, 7 and 8 days respectively. They undertook to finish the work together for Rs. 53650. Find the difference (in Rs.) between the share of A and that of B
A. 10100
B. 11100
C. 11650
D. 12560
Answer: Option B
Explanation: The ratio of shares of A, B and C = The [latex]\frac{1}{4}[/latex]:[latex]\frac{1}{7}[/latex]: [latex]\frac{1}{8}[/latex]
= [latex]\frac{14}{56}[/latex]:[latex]\frac{8}{56}[/latex]: [latex]\frac{7}{56}[/latex]= 14 : 8 : 7
Difference between the shares of A and B in ratio = [latex]\frac{6}{29}[/latex]
∴ Actual difference in value = [latex]\frac{6}{29}[/latex]× 53650 = 11,100/-
5. P is thrice as good a workman as Q and together they finish a piece of work in 24 days. The number of days taken by P alone to finish the work is:
A. 25 days
B. 22 days
C. 32 days
D. 34 days
Answer: Option C
Explanation: P's 1 days' work) : (Q's 1 days' work) = 3 : 1
(P + Q)'s = 1 days work = [latex]\frac{1}{24}[/latex]
Divide [latex]\frac{1}{24}[/latex] in the ratio 3 : 1
P's 1 day's work = [[latex]\frac{1}{24}[/latex] x [latex]\frac{3}{4}[/latex]]⇒ [latex]\frac{1}{32}[/latex]
Hence, P alone can finish the work in 32 days.