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1. The average price of 10 books is Rs.12 while the average price of 8 of these books is Rs. 11.75. Of the remaining two books, if the price of one book is 60% more than the price of the other, what is the price of each of these two books?

A. Rs. 5, Rs.7.50

B. Rs. 8, Rs. 12

C. Rs. 10, Rs. 16

D. Rs. 12, Rs. 14

Solution:

Total cost of 10 books = Rs. 120
Total cost of 8 books = Rs. 94
⇒ The cost of 2 books = Rs. 26
Let the price of each book be x and y.
⇒ x + y = 26 - - - - - -(1)
Given that the price of 1 book is 60% more than the other price

\begin{aligned} (\frac{160}{100}) y + y = 26 \\ \Rightarrow y (\frac{160}{100} + 1) = 26 \\ \Rightarrow y (\frac{160 + 100}{100}) = 26 \\ \Rightarrow y = \frac{(26 \times 100)}{260} \\ \Rightarrow y = 10 \\ Substituting y = 10 in (1) we get, \\ x + 10 = 26 \\ x = 16 \end{aligned}

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