Question

one can get 2 dozen less banana for 840rupess when the rate of banana is increased by 1 rupess per dozen then find original cost of one dozen banana​

Answer 1

Question:

One can get 2 dozen less banana for 840 rupees when the rate of banana is increased by 1 rupees per dozen then find the original cost of one dozen banana?

Answer:

Let the cost of banana per dozen be Rs. x.

Amount for which bananas are bought = Rs. 840

No. of dozens of bananas for Rs 840  = 840/x

New cost of banana per dozen = Rs. (x + 1)

New No. of dozens of bananas for Rs 840 = 840/x+1

According to given condition,

840/x – 840 / x + 1 = 2

∴ 840[1/x – 1/x+1] = 2

∴ 840 [x+1- x / x(x+1)] = 2

 ∴ 840 [1/ (x² + x)] = 2  

∴ 840 = 2(x² + x)

 ∴ 2x2 + 2x – 840 = 0

Dividing by 2, we get  

x² + x – 420 = 0  

x² – 20x + 21x – 420 = 0  

∴  x (x – 20) + 21 (x – 20) = 0

 ∴  x – 20 = 0 or x + 21 = 0  

∴  x = 20 or x = –21

∴  The cost of bananas cannot be negative.  

∴  x = 20  

The original cost of one dozen banana is Rs. 20

Step-by-step explanation:

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