Time & Work Set






Question / āĻĒā§ā§°āĻļā§āύ: Find the amount obtained in 2 years on ₹6,800 at 15% per annum compound interest, compounded annually (₹6,800 āϟāĻ•āĻžā§° āĻ“āĻĒā§°āϤ 15% āĻŦāĻžā§°ā§āώāĻŋāĻ• āϚāĻ•ā§āϰāĻŦ⧃āĻĻā§āϧāĻŋ āϏ⧁āĻĻā§° āĻšāĻžā§°āϤ 2 āĻŦāϛ⧰⧰ āĻĒāĻŋāĻ›āϤ āĻŽāĻŋāĻļā§ā§°āϧāύ (Amount) āύāĻŋā§°ā§āĻŖāϝāĻŧ āϕ⧰āĻ•āĨ¤)


A. ₹9,393 B. ₹8,641 C. ₹8,993 D. ₹7,996


 Formula / āϏ⧂āĻ¤ā§ā§° : A = P(1 + R/100​)n


 Where / āϝ'āϤ



  • P = ₹6800 Principal / āĻŽā§‚āϞāϧāύ)

  • R = 15% (Rate / āϏ⧁āĻĻā§° āĻšāĻžā§°)

  • n =  years (āĻŦāϛ⧰)


A = P(1 + R/100​)n


A = 6800(1+15/100)2 = 6800(1.15)2 = 6800 × 1.3225 = 8993


Therefore, the amount after 2 years is: â‚š8,993


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Question / āĻĒā§ā§°āĻļā§āύ: An article was purchased for ₹8,900. Its price was marked 40% above the cost price. It was then sold at a 5% discount on the marked price. What was the profit percentage ? (āĻāϟāĻž āĻŦāĻ¸ā§āϤ⧁ ₹8,900 āϤ āĻ•ā§ā§°āϝāĻŧ āϕ⧰āĻž āĻšā§ˆāĻ›āĻŋāϞāĨ¤ āχāϝāĻŧāĻžā§° āĻŽā§‚āĻ˛ā§āϝ āĻ•ā§ā§°āϝāĻŧāĻŽā§‚āĻ˛ā§āϝāϤāĻ•ā§ˆ 40% āĻŦ⧇āĻ›āĻŋ āϕ⧰āĻŋ āϚāĻŋāĻšā§āύāĻŋāϤ (Marked Price) āϕ⧰āĻž āĻš'āϞāĨ¤ āϤāĻžā§° āĻĒāĻŋāĻ›āϤ āϚāĻŋāĻšā§āύāĻŋāϤ āĻŽā§‚āĻ˛ā§āϝ⧰ āĻ“āĻĒā§°āϤ 5% ⧰⧇āĻšāĻžāχ āĻĻāĻŋ āĻŦāĻŋāĻ•ā§ā§°ā§€ āϕ⧰āĻž āĻš'āϞāĨ¤ āϞāĻžāĻ­ā§° āĻļāϤāϕ⧰āĻž āĻ•āĻŋāĻŽāĻžāύ ?)


A. 33% B. 32% C. 34% D. 35%


Shortcut / āϚāĻŽā§ āĻĒāĻĻā§āϧāϤāĻŋ

Marked Price (MP) = 140% of CP 


Selling Price (SP) = 95% of MP = 140% × 95% = 140 × 95/100 = 133% 


Thus, SP = 133% of CP 


Profit % = 133% − 100% = 33%


Ans / āωāĻ¤ā§āϤ⧰ : A. 33%


Short Tricks


CP = ₹8900


MP = 8900 ×1.40 = ₹12460


SP = 12460 × 0.95 = ₹11837


Profit = 11837 − 8900 = ₹2937 


Profit % = 2937 / 8900 × 100 = 33% 


Ans: A. 33%


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Question / āĻĒā§ā§°āĻļā§āύ: A and B together can complete a work in 6 days. B alone can complete the same work in 12 days. How many days will A alone take to complete twice the work ? (A āφ⧰⧁ B āĻ āĻāϕ⧇āϞāϗ⧇ āĻāϟāĻž āĻ•āĻžāĻŽ 6 āĻĻāĻŋāύāϤ āϏāĻŽā§āĻĒā§‚ā§°ā§āĻŖ āϕ⧰āĻŋāĻŦ āĻĒāĻžā§°ā§‡āĨ¤ B āĻ āĻ…āĻ•āϞ⧇ āĻāϕ⧇āϟāĻž āĻ•āĻžāĻŽ 12 āĻĻāĻŋāύāϤ āϏāĻŽā§āĻĒā§‚ā§°ā§āĻŖ āϕ⧰āĻŋāĻŦ āĻĒāĻžā§°ā§‡āĨ¤ A āĻ āĻ…āĻ•āϞ⧇ āϏ⧇āχ āĻ•āĻžāĻŽā§° āĻĻ⧁āϗ⧁āĻŖ āĻ•āĻžāĻŽ āϏāĻŽā§āĻĒā§‚ā§°ā§āĻŖ āϕ⧰āĻŋāĻŦāϞ⧈ āĻ•āĻŋāĻŽāĻžāύ āĻĻāĻŋāύ āϞ'āĻŦ ?)


A. 27 B. 12 C. 24 D. 25


Shortcut Trick / āϚāĻŽā§ āĻ•ā§ŒāĻļāϞ

A + B = 6 days ,  B=12 days 

A = 6 × 12 / 12 − 6 = 72/6

So, A alone completes 1 work in 12 days. āĻ…ā§°ā§āĻĨāĻžā§Ž, A āĻ āĻ…āĻ•āϞ⧇ ā§§āϟāĻž āĻ•āĻžāĻŽ 12 āĻĻāĻŋāύāϤ āϏāĻŽā§āĻĒā§‚ā§°ā§āĻŖ āϕ⧰⧇āĨ¤

For double work / āĻĻ⧁āϗ⧁āĻŖ āĻ•āĻžāĻŽā§° āĻŦāĻžāĻŦ⧇: 12 × 2 = 24 days

Ans / āωāĻ¤ā§āϤ⧰: C. 24 days (24 āĻĻāĻŋāύ)

Trick / āĻ•ā§ŒāĻļāϞ

If: (A+B) = x days, B = y days (āϝāĻĻāĻŋ (A+B) = x āĻĻāĻŋāύ āφ⧰⧁ B = y āĻĻāĻŋāύ āĻšāϝāĻŧ, āϤ⧇āĻ¨ā§āϤ⧇)

Then: A = xy / y − x 

āϤāĻžā§° āĻĒāĻŋāĻ›āϤ āĻĻ⧁āϗ⧁āĻŖ āĻ•āĻžāĻŽ āĻš'āϞ⧇ āωāĻ¤ā§āϤ⧰āĻ• 2 ⧰⧇ āϗ⧁āĻŖ āϕ⧰āĻŋāĻŦāĨ¤

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Question / āĻĒā§ā§°āĻļā§āύ: A vessel is filled 2/5​ with blue liquid. One-third of the remaining part is filled with black liquid. Then 5/6​ of the remaining part is filled with yellow liquid. The remaining 4.2 litres is white liquid. Find the total capacity of the vessel. (āĻāϟāĻž āĻĒāĻžāĻ¤ā§ā§°ā§° 2/5 āĻ…āĻ‚āĻļ āύ⧀āϞāĻž āĻĻā§ā§°ā§ąā§°ā§‡ āĻ­ā§°āĻžāĨ¤ āĻŦāĻžāϕ⧀ āĻ…āĻ‚āĻļā§° 1/3 āĻ…āĻ‚āĻļ āĻ•'āϞāĻž āĻĻā§ā§°ā§ąā§°ā§‡ āĻ­ā§°āĻž āĻšāϝāĻŧāĨ¤ āϤāĻžā§° āĻĒāĻŋāĻ›āϤ āĻŦāĻžāϕ⧀ āĻ…āĻ‚āĻļā§° 5/6  āĻ…āĻ‚āĻļ āĻšāĻžāϞāϧ⧀āϝāĻŧāĻž āĻĻā§ā§°ā§ąā§°ā§‡ āĻ­ā§°āĻž āĻšāϝāĻŧāĨ¤ āĻļ⧇āώāϤ 4.2 āϞāĻŋāϟāĻžā§° āĻŦāĻ—āĻž āĻĻā§ā§°ā§ą āĻŦāĻžāϕ⧀ āĻĨāĻžāϕ⧇āĨ¤ āĻĒāĻžāĻ¤ā§ā§°āĻŸā§‹ā§° āĻŽā§āĻ  āϧāĻžā§°āĻŋāϤāĻž āύāĻŋā§°ā§āĻŖāϝāĻŧ āϕ⧰āĻ•āĨ¤)

A. 60 L B. 78 L C. 63 L D. 72 L

Shortcut / āϚāĻŽā§ āĻĒāĻĻā§āϧāϤāĻŋ



  • 1st: Remaining after blue liquid :(āύ⧀āϞāĻž āĻĻā§ā§°ā§ą āĻ­ā§°ā§‹ā§ąāĻžā§° āĻĒāĻŋāĻ›āϤ āĻŦāĻžāϕ⧀ āĻ…āĻ‚āĻļ) :1 - 2/5 = 3/5

  • 2nd : Remaining after black liquid: (āĻ•'āϞāĻž āĻĻā§ā§°ā§ą āĻ­ā§°ā§‹ā§ąāĻžā§° āĻĒāĻŋāĻ›āϤ āĻŦāĻžāϕ⧀ āĻ…āĻ‚āĻļ) : 3/5  × (1 - 1/3) = 3/5 × 2/3 = 2/5

  • 3rd : Remaining after yellow liquid: (āĻšāĻžāϞāϧ⧀āϝāĻŧāĻž āĻĻā§ā§°ā§ą āĻ­ā§°ā§‹ā§ąāĻžā§° āĻĒāĻŋāĻ›āϤ āĻŦāĻžāϕ⧀ āĻ…āĻ‚āĻļ) : 2/5 × (1−5/6) = 2/5 × 1/6 = 1/15


So, the white liquid is 1/15 of the vessel. āĻ…ā§°ā§āĻĨāĻžā§Ž āĻŦāĻ—āĻž āĻĻā§ā§°ā§ą āĻĒāĻžāĻ¤ā§ā§°āĻŸā§‹ā§° 1/15 āĻ…āĻ‚āĻļāĨ¤


Given: 1/15 = 4.2 L


Therefore, Total Capacity = 4.2 × 15 = 63 L


Ans / āωāĻ¤ā§āϤ⧰ : C. 63 Litres (63 āϞāĻŋāϟāĻžā§°)


Trick / āĻ•ā§ŒāĻļāϞ: Remaining fraction = Multiply all remainders (āĻŦāĻžāϕ⧀ āĻ…āĻ‚āĻļ = āϏāĻ•āϞ⧋ remainder āϗ⧁āĻŖ āϕ⧰āĻ•): (1 - 2/5) (1 - 1/3) (1  -5/6) = 1/15



Ans = 63 Litres / 63 āϞāĻŋāϟāĻžā§°






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Trick–1 : Men–Days–Work (Basic Rule)


Rule: Men × Days = Constant Work 


Ex 1. 12 men can do a work in 20 days. How many days will 5 men take ?


Soln


12×20 = A


A = 240/55 = 48


Ans: 48 days


Ex 2. 15 boys can do a work in 20 days. How many days will 10 boys take? (Boys Problem)


Soln


15×20 = 10 × A


Ans: 30 days


Trick–2 : Men–Women–Work


Rule: First convert all workers into one unit using efficiency.


Ex 3. 1 Man = 2 Women, 5 men + 4 women can do work in 36 days. How many days will 4 men take ?


Soln


5M + 4W = 5M + 2M = 7M


7 × 36 = 4 × A


Ans: 63 days


Trick - 3 : Efficiency ↔ Time


Rule: Efficiency 1/Time


Ex 4. Efficiency of A : B = 3 : 2 Find time ratio.


Soln


Time = 2:3


Ans: 2 : 3


Trick - 4 : Wages & Efficiency


Rule: Wages Efficiency


Ex 5.  A, B, C complete a work together. Efficiency ratio = 15 : 12 : 10.Total wages = ₹7400. Find B’s share.


Soln


Total ratio = 15+12+10 = 37


B = 12/37×7400


B = ₹2400


Ans: ₹2400


Trick - 5 : Given Time of Each, Find Wages


Ex 6.  A works 15 days, B works 12 days, C works 10 days. Total wages = ₹7400. Efficiency same.


Soln


Ratio = 15:12:10


Sum = 37


A = 15/37×7400=₹3000


Ans: ₹3000