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EFFICIENCY IS INVERSLY PROPORTIONAL WITH THE DURATION (DAYS, HOURS, ETC.)
E α ^{1}/_{D }
_{E D = CONSTANT}
_{E1 × D1 = E2 × D2}
Q1. 
Seeta can complete a work in 45 days. Geeta is 25% more efficient than Seeta. In how many days can they together complete the work? 
A. 36 

B. 40 

C. 20 

D. 48 
Geeta is 25% more efficient than Seeta
Let the efficiency of Seeta = 4
Efficiency of Geeta = 5
E1D1 = E2D2
4 * 45 = ( 4 + 5 ) * X
X = 20
Q2. 
Aryan can complete a piece of work in 9 days. Arav is 25% less efficient than Arav. In how many days can Arav complete the work alone? 
A. 24 

B. 18 

C. 36 

D. 12 
Aryan can complete a piece of work in 9 days. Arav is 25% less efficient than Arav
Let the efficiency of Aryan = 4
Efficiency of Arav = 3
4 * 9 = 3 * x
x = 12
Q3. 
Karan can complete a piece of work in 30 days. Rajan is 50% more efficient than Karan. In how many days can Rajan complete the work? 
A. 60 

B. 15 

C. 20 

D. 10 
Karan can complete a piece of work in 30 days. Rajan is 50% more efficient than Karan.
Let the efficiency of Karan = 2
Efficiency of Rajan = 3
We know, E1D1 = E2D2 (Read the concepts and watch the video of this concept)
2 × 30 = 3 × x
x = 20
Q4. 
Rajat can complete a piece of work in 40 days. Sujit is 50% as efficient as Rajat. In how many days can Sujit alone do the work? 
A. 20 

B. 80 

C. 60 

D. 50 
50% efficiency means double the time required.
answer is 40 × 2 = 80 days
Q1. 
A is twice as efficient than B and together they can do the same work in as much time as C and D together. If C and D can complete the work in 20 and 30 days respectively working alone, then in how many days can A complete the work alone? 
A. 30 

B. 24 

C. 18 

D. 12 
A is twice as efficient than B and together they can do the same work in as much time as C and D together. If C and D can complete the work in 20 and 30 days
Let the total work = 60 units
C does 3 and D does 2 units per day
C & D together can complete in 60/5 = 12 days.
The efficiency ratio of A and B = 2 : 1
2 * x = (2 + 1) 12
x = 18 days
Q2. 
Omm is 50% as efficient as Shiv. Shanti is 25% less efficient than Omm. If Shiv alone can complete the work in 60 days, In how many days can they together complete the work? 
A. 36 

B. 32 

C. 24 

D. 12 
Omm is 50% as efficient as Shiv. Shanti is 25% less efficient than Omm.
Let the Efficiency of Shiv = 8
( Note:8 = 2*4 which are the denominator of fractions)
Efficiency of Omm = 4
Efficiency of Shanti = 3
8 * 60 = (8 + 4 + 3) * x
x = 32