Tuesday, 29 January 2019

Trick/Theory:- If X1 men or Y1 women can complete a work in D days. 
Then, X2 men and Y2 women together can complete the same work in -

D/(X2/X1 + Y2/Y1)  or DX1Y1/(X1Y2 + X2Y1)

or,

Let's solve some Questions....


Q-1) If 4 men or 6 women can finish a piece of work in 20 days, in how many days can 6 men and 11 women finish it ?

a) 6 days
b) 7 days
c) 8 days
d) 9 days

Sol:- If 4 men (X1) or 6 women (Y1) can finish a piece of work in 20 days (D).
In how many days can 6 men (X2) and 11 women (Y2) finish it ?

Now apply 1st Maths Tricks for Time and Work Questions 

D/(X2/X1 + Y2/Y1)

Now put X1=4, Y1=6, D=20, X2=6 and Y2=11

D/(X2/X1 + Y2/Y1)

20 (6/4 + 11/6)

20 (20/6)

20 * 6 20

= 6

or,
Now apply 2nd Maths Tricks for Time and Work Questions 

DX1Y1/(X1Y2 + X2Y1)

Now put X1=4, Y1=6, D=20, X2=6 and Y2=11

DX1Y1/(X1Y2 + X2Y1)

20 * 4 * 6 / (4*11 + 6*6)

20 * 4 * 6 / (44 + 36)

20 * 4 * 6 80

4 * 6 4

= 6

Your answer a) 6 days. [So, In 6 days can 6 men and 11 women finish it.]


Q-2) If 6 men or 10 women can reap a field in 86 days, how long will 10 men and 12 women take to reap it ?

a) 25 days
b) 30 days
c) 35 days
d) 40 days

Sol:- If 6 men (X1) or 10 women (Y1) can reap a field in 86 days (D), 
how long will 10 men (X2) and 12 women (Y2) take to reap it ?

Now apply 1st Maths Tricks for Time and Work Questions 

D/(X2/X1 + Y2/Y1)

Now put X1=6, Y1=10, D=86, X2=10 and Y2=12

  D/(X2/X1 + Y2/Y1)

86 (10/6 + 12/10)

86 (5/3 + 6/5)

86 (43/15)

86 * 15 43

= 2 * 15

= 30

or,
Now apply 2nd Maths Tricks for Time and Work Questions 

DX1Y1/(X1Y2 + X2Y1)

Now put X1=6, Y1=10, D=86, X2=10 and Y2=12

DX1Y1/(X1Y2 + X2Y1)

86 * 6 * 10 (6*12 + 10*10)

86 * 6 * 10 (72 + 100)

86 * 6 * 10 172

= 3 * 10

= 30

Your answer b) 30 days. [So, In 30 days 10 men and 12 women take to reap it.]


Q-3) If 3 men or 9 boys can finish a piece of work in 21 days, in how many days can 5 men and 6 boys together do the same piece of work ?

a) 8 days
b) 12 days
c) 14 days
d) N.O.T.

Sol:- If 3 men (X1) or 9 boys (Y1) can finish a piece of work in 21 days (D).
In how many days can 5 men (X2) and 6 boys (Y2) together do the same piece of work ?

Now apply 1st Maths Tricks for Time and Work Questions 

D/(X2/X1 + Y2/Y1)

Now put X1=3, Y1=9, D=21, X2=5 and Y2=6

D/(X2/X1 + Y2/Y1)

21 (5/3 + 6/9)

21 (5/3 + 2/3)

21 7/3

21 * 3 7

= 3 * 3

= 9


or,
Now apply 2nd Maths Tricks for Time and Work Questions 

DX1Y1/(X1Y2 + X2Y1)

Now put X1=3, Y1=9, D=21, X2=5 and Y2=6

DX1Y1/(X1Y2 + X2Y1)

21 * 3 * 9 (3*6 + 5*9)

21 * 3 * 9 (18 + 45)

21 * 27 63

= 9

Your answer d) N.O.T days. [So, In 9 days can 5 men and 6 boys together do the same piece of work.]


Q-4) If 2 men or 4 women can finish a piece of work in 44 days, in how many days can 3 men and 5 women finish it ?

a) 8 days
b) 12 days
c) 15 days
d) 16 days

Sol:- If 2 men (X1) or 4 women (Y1) can finish a piece of work in 44 days (D).
In how many days can 3 men (X2) and 5 women (Y2) finish it ?

Now apply 1st Maths Tricks for Time and Work Questions 

D/(X2/X1 + Y2/Y1)

Now put X1=2, Y1=4, D=44, X2=3 and Y2=5

D/(X2/X1 + Y2/Y1)

44 (3/2 + 5/4)

44 11/4

44 * 4 11

= 4 * 4

= 16


or,
Now apply 2nd Maths Tricks for Time and Work Questions 

DX1Y1/(X1Y2 + X2Y1)

Now put X1=2, Y1=4, D=44, X2=3 and Y2=5

DX1Y1/(X1Y2 + X2Y1)

 = 44 * 2 * 4 (2*5 + 3*4)

44 * 8 (10 + 12)

44 * 8 22

= 2 * 8

= 16

Your answer d) 16 days. [So, In 16 days can 3 men and 5 women finish it.]


Q-5) If 10 men or 18 boys complete a work in 15 days. Then, in how many days, 25 men and 15 boys will complete the work ?

a) 9 2 days
b) 9 days
c) 18 days
d) 36 days

Sol:- If 10 men (X1) or 18 boys (Y1) complete a work in 15 days (D).
In how many days, 25 men (X2) and 15 boys (Y2) will complete the work ?

Now apply 1st Maths Tricks for Time and Work Questions 

D/(X2/X1 + Y2/Y1)


Now put X1=10, Y1=18, D=15, X2=25 and Y2=15

D/(X2/X1 + Y2/Y1)

15 (25/10 + 15/18)

15 (5/2 + 5/6)

15 20/6

15 * 6 20

3 * 6 4

3 * 3 2

9 2

or,
Now apply 2nd Maths Tricks for Time and Work Questions 

DX1Y1/(X1Y2 + X2Y1)

Now put X1=10, Y1=18, D=15, X2=25 and Y2=15

DX1Y1/(X1Y2 + X2Y1)

15 * 10 * 18 (10*15 + 25*18)

15 * 10 * 18 (150 + 450)

15 * 10 * 18 600

18 4

9 2

Your answer a9 2 days. [So, In 9/2 days 25 men and 15 boys will complete the work.]

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