Model 1 Basics On Time & Work Practice Questions Answers Test With Solutions & More Shortcuts
TIME & WORK PRACTICE TEST [7  EXERCISES]
Model 1 Basics On Time & Work
Model 2 Formula Method ‘M1D1W1 = M2D2W2’
Model 3 Man Leaves & Joins
Model 4 Working With Man, Woman, Child
Model 5 Split & Fraction Of Work
Model 6 Efficiency Of The Worker
Model 7 Working With Individual Wages
Question : 16 [SSC CGL Prelim 2005]
A and B can complete a piece of work in 30 days, B and C in 20 days, while C and A in 15 days. If all of them work together, the time taken in completing the work will be
a) 13$1/3$ days
b) 12$2/3$ days
c) 10 days
d) 12 days
Answer »Answer: (a)
Work done by (A + B) in 1 day = $1/30$
Work done by (B + C) in 1 day = $1/20$
Work done by (C + A) in 1 day = $1/15$
On adding,
Work done by 2 (A +B + C) in 1 day
= $1/30 + 1/20 + 1/15 = {2 + 3 + 4}/60$
= $9/60 = 3/20$
Work done by (A + B + C) in 1 day = $3/40$
(A + B + C) will do the work in $40/3 = 13{1}/3$ days
Using Rule 5,
Time taken = ${2 × 30 × 20 × 15}/{30 × 20 + 20 × 15 + 15 × 30}$
= $18000/{600 + 300 + 450}$
= $18000/1350 = 13{1}/3$ days
Question : 17 [SSC CHSL 2011]
A and B can do a piece of work in 10 days. B and C can do it in 12 days. A and C can do it in 15 days. How long will A take to do it alone ?
a) 30 days
b) 40 days
c) 24 days
d) 20 days
Answer »Answer: (c)
(A+B)’s 1 day’s work = $1/10$
(B + C)’s 1 day’s work = $1/12$
(C + A)’s 1 day’s work = $1/15$
On adding all three,
2(A + B + C)’s 1 day’s work = $1/10 + 1/12 + 1/15$
= ${6 + 5 + 4}/60 = 15/60 = 1/44$
(A + B + C)’s 1 day’s work = $1/8$
A’s 1 day’s work = $1/8  1/12$
= ${3  2}/24 = 1/24$
A will complete the work in 24 days.
Using Rule 19,
A alone can do in = ${2 × x × y × z}/{xy + yz  zx}$
= ${2 × 10 × 12 × 15}/{10 × 12 + 12 × 15  15 × 10}$
= $3600/{120 + 180  150}$
= $3600/150$ = 24 days
Question : 18 [SSC CPO S.I.2003]
A, B and C can complete a piece of work in 24, 6 and 12 days respectively. Working together, they will complete the same work in
a) 4 days
b) 3${3}/7$ days
c) $1/4$ day
d) $7/24$ day
Answer »Answer: (b)
A’s 1 day’s work = $1/24$
B’s 1 day’s work = $1/6$
C’s 1 day’s work = $1/12$
(A + B + C)’s 1 day’s work
=$1/24 + 1/6 + 1/12 = {1 + 4 + 2}/24 = 7/24$
The work will be completed by them in $24/7$ i.e., 3$3/7$ days
Using Rule 3
If A can do a work in 'x' days, B can do the same work in 'y' days, C can do the same work in 'z' days then, total time taken by A, B and C to complete the work together = $1/{1/x + 1/y + 1/z} = {xyz}/{xy + yz + zx}$and
If workers are more than 3 then total time taken by A, B, C ...... so on to complete the work together = $1/{1/x + 1/y + 1/z + ...}$
Time taken = ${24 × 6 × 12}/{24 × 6 + 6 × 12 + 24 × 12}$
= $1728/{144 + 72 + 288}$
= $1728/504 = 24/7 = 3{3}/7$ days
Question : 19 [SSC MTS 2011]
A and B can do a piece of work in 72 days. B and C can do it in 120 days, A and C can do it in 90 days. In how many days all the three together can do the work ?
a) 150 days
b) 60 days
c) 80 days
d) 100 days
Answer »Answer: (b)
(A+B)’s 1 day’s work = $1/72$,
(B+C)’s 1 day’s work = $1/120$,
(C+A)’s 1 day’s work = $1/90$
On adding all three
2 (A + B + C)'s 1 days work = $1/72 + 1/120 + 1/90$
= ${5 + 3 + 4}/360 = 1/30$
(A+B+C)’s 1 day’s work = $1/60$
(A+B+C) will do the work in 60 days.
Using Rule 5,
Time taken = ${2 × 72 × 120 × 90}/{72 × 120 + 120 × 90 + 72 × 90}$
= $1555200/{8640 + 10800 + 6480}$
= $1555200/25920$ = 60 days
Question : 20 [SSC SO 2007]
If A and B together can complete a work in 18 days, A and C together in 12 days and B and C together in 9 days, then B alone can do the work in
a) 40 days
b) 30 days
c) 18 days
d) 24 days
Answer »Answer: (d)
(A + B)’s 1 day’s work = $1/18$
(B + C)’s 1 day’s work = $1/9$
(A + C)’s 1 day’s work = $1/12$
Adding all the above three,
2 (A + B + C)’s 1 day’s work = $1/18 + 1/9 + 1/12$
= ${2 + 4 + 3}/36 = 9/36 = 1/4$
(A + B + C)’s 1 day’s work = $1/8$
B’s 1 day’s work = (A + B + C)’s 1 day’s work  (A + C)’s 1 day’s work
= $1/8  1/12 = {3  2}/24 = 1/24$
Hence, B alone can do the work in 24 days.
Using Rule 19,
B alone can do in = ${2 × 18 × 9 × 12}/{18 × 9 + 12 × 9 + 12 × 18}$
= ${36 × 108}/{162 + 108 + 216} = {36 × 108}/162$ = 24 days
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Model 1 Basics On Time & Work Shortcuts »
Click to Read...Model 1 Basics On Time & Work Online Quiz
Click to Start..TIME & WORK SHORTCUTS AND TECHNIQUES WITH EXAMPLES

Model 1 Basics On Time & Work
Defination & Shortcuts … 
Model 2 Formula Method ‘M1D1W1 = M2D2W2’
Defination & Shortcuts … 
Model 3 Man Leaves & Joins
Defination & Shortcuts … 
Model 4 Working With Man, Woman, Child
Defination & Shortcuts … 
Model 5 Split & Fraction Of Work
Defination & Shortcuts … 
Model 6 Efficiency Of The Worker
Defination & Shortcuts … 
Model 7 Working With Individual Wages
Defination & Shortcuts …
QUANTITATIVE APTITUDE CATEGORIES

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» Advance Math

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» Simple Interest

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» Mensuration

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