If xerox paper costs 5 cents a sheet and a buyer gets 10% discount on all xerox paper one buys after the first 2000 papers and 20% discount after first 10000 papers, how much will it cost to buy 15000 sheets of xerox paper?  Choose the correct choice from the following options:
A) $ 1250
B) $ 700
C) $ 1350
D) $ 900
E) $ 1000

Rationale: 30 sec approach - solve it using approximation 15000 sheet at full price , 5 cent = 750 15000 sheet at max discount price , 4 cent = 600 your ans got to be between these two . ans b it is .
Answer: B