650.A can do piece of work in 30 days while B can do it in 40 days. In how many days can A and B working together do it ?
70 days
42 ¾ days
27 1/7 days
17 1/7 days
Explanation:
A's one day's work = 1/30 B's one day's work = 1/40 (A + B)'s one day's work = 1/30+1/40=7/120 A and B together will take 120/7 days=17 $\dfrac{1}{7}$ days
A's one day's work = 1/30 B's one day's work = 1/40 (A + B)'s one day's work = 1/30+1/40=7/120 A and B together will take 120/7 days=17 $\dfrac{1}{7}$ days
651.A and B can together do a piece of work in 15 days. B alone can do it in 20 days. In how many days can A alone do it ?
30 days
40 days
45 days
60 days
Explanation:
(A + B)’s 1 day’s work = $\dfrac{1}{15}$ B’s 1 day’s work = $\dfrac{1}{20}$ ∴ A’s 1 day’s work = $\frac{1}{15}$-$\dfrac{1}{20}$ = $\dfrac{4-3}{60}$= $\dfrac{1}{60}$ ∴ A alone will do the work in 60 days.
(A + B)’s 1 day’s work = $\dfrac{1}{15}$ B’s 1 day’s work = $\dfrac{1}{20}$ ∴ A’s 1 day’s work = $\frac{1}{15}$-$\dfrac{1}{20}$ = $\dfrac{4-3}{60}$= $\dfrac{1}{60}$ ∴ A alone will do the work in 60 days.
652.8 children and 12 men complete a certain piece of work in 9 days. If each child takes twice the time taken by a man to finish the work, in how many days will 12 men finish the same work ?
8
15
9
12
Explanation:
2 children = one man
8 children + 12 men = 4 men + 12 men
= 16 men
12 :16 = 9 : x (indirect)
12x=16×9=144
x = 12
2 children = one man
8 children + 12 men = 4 men + 12 men
= 16 men
12 :16 = 9 : x (indirect)
12x=16×9=144
x = 12
653.12 men or 18 women can reap a field in 14 days. The number of days that 8 men and 16 women will take to reap it is
5 days
7 days
8 days
9 days
Explanation:
12 men can reap the field in 14 day
⇒ 1 man can reap the field in 12 x 14 = 168 days
⇒ 8 men can reap the field in 168 ÷ 8 = 21 days
⇒ 1 day =1 ÷ 21 = 1/21 of the field
18 women can reap the field in 14 day
⇒ 1 woman can reap the field in 18 x 14 = 252 days
⇒ 16 women can reap the field in 252 ÷ 16 = 15.75 of the field
⇒ 1 day = 1 ÷ 15.75 = 4/63 of the field
So in one day, 12 men and 18 women can reap:
1/21 + 4/63 = 1/9 of the field
Find the number of days needed:
1/9 fo the field = 1 day
9/9 of the field = 1 x 9 = 9 days
Answer: They will take 9 days to reap the field.
12 men can reap the field in 14 day
⇒ 1 man can reap the field in 12 x 14 = 168 days
⇒ 8 men can reap the field in 168 ÷ 8 = 21 days
⇒ 1 day =1 ÷ 21 = 1/21 of the field
18 women can reap the field in 14 day
⇒ 1 woman can reap the field in 18 x 14 = 252 days
⇒ 16 women can reap the field in 252 ÷ 16 = 15.75 of the field
⇒ 1 day = 1 ÷ 15.75 = 4/63 of the field
So in one day, 12 men and 18 women can reap:
1/21 + 4/63 = 1/9 of the field
Find the number of days needed:
1/9 fo the field = 1 day
9/9 of the field = 1 x 9 = 9 days
Answer: They will take 9 days to reap the field.
1226.A can do a work in 14 days and working together A and B can do the same work in 10 days. In what time can B alone do the work?
25 days
30 days
23 days
35 days
Explanation:
1 day work of A=1/14
1 day work of (A+B)=1/10
Given:A+B=1/10
or,1/14+B=1/10
or,B=1/10-1/14
Or,B=2/70=1/35
Now, 1/35 part of work is done in 1 day by B.
So,1 work will be done in 1÷1/35=35 days.
B can alone do the work in 35 days.
1 day work of A=1/14
1 day work of (A+B)=1/10
Given:A+B=1/10
or,1/14+B=1/10
or,B=1/10-1/14
Or,B=2/70=1/35
Now, 1/35 part of work is done in 1 day by B.
So,1 work will be done in 1÷1/35=35 days.
B can alone do the work in 35 days.
1227.Manu, Manju and Maya can do a work in 90, 30 and 45 days respectively. If they work together, in how many days will they complete work?
15 days
10 days
20 days
25 days
Explanation:
manu,manju and maya work 1/30
manju 1/30
maya 1/45
Manu,manju and maya
Total:
1/30+1/30+1/45= 1+2+3/30= 6/15+6=1/15
:: the answer is 15 days
manu,manju and maya work 1/30
manju 1/30
maya 1/45
Manu,manju and maya
Total:
1/30+1/30+1/45= 1+2+3/30= 6/15+6=1/15
:: the answer is 15 days
1228.40 men can catch 200 sharks in 20 days working 6 hours a day. In how many days 25 men can catch 300 sharks working 4 hours a day?
30
34
36
20
Explanation:
1st. 40 men can catch 200 sharks in 20 days * 6 hrs/day.
Thus, 1 man can catch 5 sharks in 20*6 hours
2nd. 25 men can catch 300 sharks in x days * 4 hrs/day
Therefore, 1 man can catch 6 sharks in 4*x hours.
(Notice that number of hours required, 4*x, has not been disturbed.)
Forward,
1 . 1 man can catch 5*6 sharks in 6*20*6 hours.
2. 1 man can catch 6*5 sharks in 5*4*x hours.
Calculations done in 1 and 2 are independent of each other.
All other values being equal, equating the number of hours from 1 and 2 we find x = 36.
Therefore, 25 men can catch 300 sharks working 4 hours a day in 36 days.
1st. 40 men can catch 200 sharks in 20 days * 6 hrs/day.
Thus, 1 man can catch 5 sharks in 20*6 hours
2nd. 25 men can catch 300 sharks in x days * 4 hrs/day
Therefore, 1 man can catch 6 sharks in 4*x hours.
(Notice that number of hours required, 4*x, has not been disturbed.)
Forward,
1 . 1 man can catch 5*6 sharks in 6*20*6 hours.
2. 1 man can catch 6*5 sharks in 5*4*x hours.
Calculations done in 1 and 2 are independent of each other.
All other values being equal, equating the number of hours from 1 and 2 we find x = 36.
Therefore, 25 men can catch 300 sharks working 4 hours a day in 36 days.
1229.Amit and Ananthu can do a work in 15 days and 25 days respectively. Amit started the work and left after 3 days. Ananthu took over and completed the work. In how many days was the total work completed?
28 days
20 days
23 days
25 days
Explanation:
Amit’s one day’s work= 1/15
Amit’s 3 day’s work = 1/15 *3 = 1/15
Work left= 1-1/5 = 4/5
Ananthu’s one day’s work= 1/25
Ananthu can do work in = 4/5*25 = 20 days
So total days = 25+3 = 28 days
Amit’s one day’s work= 1/15
Amit’s 3 day’s work = 1/15 *3 = 1/15
Work left= 1-1/5 = 4/5
Ananthu’s one day’s work= 1/25
Ananthu can do work in = 4/5*25 = 20 days
So total days = 25+3 = 28 days
1230.If A is thrice as fast as B and together can do a work in 21 days. In how many days A alone can do the work?
36 days
42 days
28 days
54 days
Explanation:
let 'x' be the number of days worked by 'A'
A = 3x
B = x
=>1/3x + 1/x = 1/21
=>4/3x = 1/21
=>3x = 21*4
=>x = (21*4)/3
=>x = 7*4
=>x = 28
Hence, 'A' can do the same work alone in 28 days.
let 'x' be the number of days worked by 'A'
A = 3x
B = x
=>1/3x + 1/x = 1/21
=>4/3x = 1/21
=>3x = 21*4
=>x = (21*4)/3
=>x = 7*4
=>x = 28
Hence, 'A' can do the same work alone in 28 days.
1231.9 men can do a work in 12 days working 4 hours a day. In how many days can 6 men do the same work, working 8 hours a day?
18
9
10
8
Explanation:
Let d be the number of days it took to complete the work if 6 men do the same work, working 8 hours a day
If M1 men can do the work in working H1 hours per day and M2 men can do the same work in working H2 hours per day, then
M1H1=M2H2
=> $ 9 \times 12 \times 4 $ =$6 \times 8 \times d $
=>d=$\dfrac{9 \times 12 \times 4 }{48}$
=>d= 9 days
Let d be the number of days it took to complete the work if 6 men do the same work, working 8 hours a day
If M1 men can do the work in working H1 hours per day and M2 men can do the same work in working H2 hours per day, then
M1H1=M2H2
=> $ 9 \times 12 \times 4 $ =$6 \times 8 \times d $
=>d=$\dfrac{9 \times 12 \times 4 }{48}$
=>d= 9 days
1232.Rohit and Rohan can complete a work in 12 days and 6 days respectively. How much time will they take when working together?
4
3
5
2
1233.Sita and Sinu together can do a work in 50 days. With the help of Smitha, they completed the work in 6 days and earn Rs.250. What is the share of Sinu if Sita alone can do the work in 100 days?
Rs.15
Rs.18
Rs.20
Rs.25
1234.A and B can do a work in 60 days; B and C can do it in 120 days; A and C can do it in 80 days. In what time A alone can do the work?
100
90
80
70
1235.Renu can do a piece of work in 6 days, but with the help of her friend Suma , she can do it in 4 days. In what time Suma can do it alone?
10
12
14
15
1236.A can finish a work in 20 days, B in 15 days and C in 12 days. B and C start the work but are forced to leave after 2 days. The remaining work was done by A in :
10
11
13
14
1237.Anu can do a work in 6 days and Binu alone in 9 days. Anu and Binu undertook to do it for Rs.4500. With help of Minu, they completed the work in 3 days. How much is to be paid to Minu and Anu?
Rs.750, Rs.2000
Rs.800, Rs.1250
Ram, Krish and Bhim can complete a work in 30 days. If Ram and Krish together can complete the same work in 40 days, then how long will Bhim take to complete it?
Rs.750, Rs.2000
Rs.800, Rs.1250
Ram, Krish and Bhim can complete a work in 30 days. If Ram and Krish together can complete the same work in 40 days, then how long will Bhim take to complete it?
Rs.750, Rs.2250
Rs.2000, Rs.750
60
80
1238.3 workers transfer a tool weighing 120kg in 12 seconds. How many men are required to transfer it in 9 seconds?
100
120
4
5
There is enough provisions for 600 men in an army camp for 25 days. If there were 300 men less, how long will the provision last?
1240.2 men and 4 boys can complete a work in 4 days. 5 men and 6 boys can complete the same work in 3 days. The work done by 2 boys is equal to the work of how many men?
45 days
50 days
4
5
A is twice as good a workman as B and together they complete a work in 12 days. In how many days A alone can do the work?