A candidate who gets 30% of the marks fails by 50 marks. But another candidate who gets 45% marks gets 25 marks more than necessary for passing. Find the number of marks for passing?

A. Rs. 6876.10
B. Rs. 6999.20
C. Rs. 6654
D. Rs. 7000

A. neither increased nor decreased
B. increased by 1 %
C. decreased by 1 %
D. decreased by 10 %
Explanation:
Let original length = l units and original breadth = b units
Then original Area = lb sq. Units
New length = (110/100 l) units = (11 l)/10 units
New breadth = (90/100 b) units = (9 l)/10 units
New area = (11l/10 × 9b/10) sq. Units = 99lb/100 sq. units
Decrease in area = (lb- 99lb/100)sq units = lb/100 sq. units
Decrease in area = (lb/100 × 1/lb ×100) % = 1 %
Decrease by = 1 %