1. 2 men and 7 women complete a work in 14 days, while 3 men and 8 women complete the same work in 11 days. I n how many days will 8 men and 6 women complete 3 times of this work ?
Answer: Option B
Explanation
Let work done by a man in a day = x units
Let work done by a woman in a day = y units
(2x + 7y) × 14 = (3x + 8y) 11
28x + 98 y = 33x + 88y
5x = 10 y
x = 2y.
work (2x + 7y) × 14
= (2 × 2y + 7y) × 14 = 154 y.
3 times work will be done in
[latex]\frac{(154y) * 3}{8x + 6y}[/latex]
[latex]\frac{(154y) * 3}{22y}[/latex] = 21 days
2. To do a certain piece of work B takes four times as long as A and C together and C takes three times as long as A and B together. If all the three working together complete the work in 12 days, how long (in days) would A alone take to complete the work?
A. [latex]21 \frac{9}{11}[/latex]
B. [latex]26 \frac{2}{3}[/latex]
C. 48
D. 60
Answer: Option A
Explanation
Let A alone takes x days to do the work.
Let B alone takes y days to do the work.
Let C alone takes 2 days to do the work.
According to the question
[latex]\frac{1}{x}[/latex] ÷ [latex]\frac{1}{2}[/latex] = [latex]\frac{4}{y}[/latex]
[latex]\frac{1}{x}[/latex] ÷ [latex]\frac{1}{2}[/latex] = [latex]\frac{3}{7}[/latex]
Also [latex]\frac{1}{x}[/latex] ÷ [latex]\frac{1}{y}[/latex] ÷ [latex]\frac{1}{2}[/latex] = [latex]\frac{1}{12}[/latex]
Solving for x
x = [latex]\frac{4 * 60}{11}[/latex] = [latex]21 \frac{9}{11}[/latex]
3. If 6 men and 8 women can do a piece of work in 10 days while 5 men and 15 women can do the same work in 8 days? I n how many days will 15 men and 20 women do the same work?
Answer: Option C
Explanation
Let work done by a man = x units in one day
Let work done by a woman = y units in one day
According to the question
(6x + 8y) 10 = (5x + 15y)8
60x + 80y = 40x + 120y
20x = 40y = x = 2y
i.e, Time = [latex]\frac{(6x ÷ 8y) * 10}{15x ÷ 20y}[/latex]
= [latex]\frac{200y}{50y}[/latex] = 4 days
4. 8 men and 12 women can do a piece of work in 5 days, while 6 men and 8 women can do it in
7 days. The time (in days) taken by two women and one man to do the same work is
Answer: Option C
Explanation
Let x units of work be done by a man in one day.
Let y units of work be done by a woman in one day
(8x + 12y)5 = (6x + 8y)7
40x + 60y = 42x + 56y
2x = 4y
x = 2y
i.e, Time = [latex]\frac{(8x ÷ 12y) * 5}{x ÷ 2y}[/latex]
= [latex]\frac{(8x * 5 * y)}{2y}[/latex] = 35 days
5. Two pipes X and Y can fill a tank in 15 and 20 minutes respectively. If both the pipes are opened together after how much time pipe y should be turned off so that the tank is full in 12 minutes?
A. 3 minutes
B. 4 minutes
C. 5 minutes
D. 6 minutes
Answer: Option B
Explanation
Let Tank capacity be 300 litres.
i.e, filling speed of x
[latex]\frac{300}{20}[/latex] = 20 l/min
filling speed of y
[latex]\frac{300}{15}[/latex] = 15 l/min
Let pipe of be turned off after + minutes
According to the question
20 × 12 + 15 × t = 300
t = 4 mins