Question

Raju bought some books in Rs. 1000. If he wants to buy 5 more books in same price then average cost of book is reduced by Rs 10. Find number of books raju ​

Answer 1

Let the number of books be = x.

Total cost of the books = Rs. 60.

∴ Cost of each book =Rs.

x

60

If the number of books is (x + 5), then the cost of each book = Rs.

x+5

60

Difference in cost is one rupee = Cost of each book when number of books is (x) - Cost of each book when number of books is (x + 5)

x

60

−

x+5

60

=1

x(x+5)

60(x+5)−60x

=1

x

2

+5x

60x+300−60x

=1

x

2

+5x=300

x

2

+5x−300=0

x

2

+20x−15x−300=0

x(x+20)−15(x+20)=0

(x+20)(x−15)=0

x+20=0 or x−15=0

∴x=−20 or x=15

∴ Number of books = x = 15

Number of books cannot be negative. Hence, -20 is rejected.

∴ Cost of each book =

x

60

=

15

60

=Rs.4

Answer 2

Answer:

koi nhi

mujhe bura nhi laga