A publishing company plans to publish a book. From the sales data of other publisher of similar books, it works out the demand function for the book as:                                               

Q = 5000 – 5P

Find out

i)                  Demand curve

ii)                Number of book sold at P = Rs. 25

iii)              Price for selling 2500 copies

iv)              Price for zero sales

Elasticity for fall in price from Rs. 25 to Rs. 20