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SSC CGL Tier1 Quantitative Aptitude Time and Work Test 1

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
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.
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
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.
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.
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
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.
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
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.
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
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