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An empty fuel tank of a car was filled with A type petrol. When the tank was half-empty, it was filled with B type petrol. Again when the tank was half-empty, it was filled with A type petrol. When the tank was half-empty again, it was filled with B type petrol. What is the percentage of A type petrol at present in the tank ?

A. 37.5%

B. 35.5%

C. 30%

D. 60%

Answer: Option A

Solution(By Examveda Team)

Let the capacity of the tank be 100 litres.
Then,
Initially :
A type petrol = 100 litres
After first operation :
A type petrol = $$\left( {\frac{{100}}{{2}}} \right)$$ = 50 litres ;
B type petrol = 50 litres
After second operation :
A type petrol = $$\left( {\frac{{50}}{2} + 50} \right)$$  = 75 litres
B type petrol = $$\left( {\frac{{50}}{2}} \right)$$ = 25 litres
After third operation :
A type petrol = $$\left( {\frac{{75}}{2}} \right)$$ = 37.5 litres
B type petrol = $$\left( {\frac{{25}}{2} + 50} \right)$$  = 62.5 litres
∴ Required percentage = 37.5%

This Question Belongs to Arithmetic Ability >> Percentage

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Comments ( 1 )

  1. Bunnu 678
    Bunnu 678 :
    2 years ago

    Let capacity of full tank x
    X= a(filled with a-typ petrol)
    After 1st operation
    X=a/2+b/2
    After 2nd operation
    X=(a/2+b/2)/2 + a/2
    After 3rd operation
    X={(a/2+ b/2)/2}/2 + b/2
    After solving
    X=3/8a + 5/8b
    So remaining a-typ petrol=3/8 ×100 =37.5%

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