A. 53.33
B. 54.68
C. 55
D. None of these
55 students get average marks of 55%.
so 55*50=2750
similarly 60*55=3300
& 60*45=2700
now total no of marks obtain by all students of three batches= 2750+3300+2700=8750/=
Total no of students= 55+60+45=160.
By dividing total marks on each student , we get average marks obtain by each student
so 8750/160 = 54.68
Solution Added by: MUHAMMAD SHOAIB

A. 14.85%
B. 9.98%
C. 16.20%
D. 14.50%
Solution by Ahmad hassan :
Actually, the question is this.
If a person sells his car in 50000 rupees and got 17% profit. What will be the profit in percentage if he sold this car in 47000 rupees?
Solution
Profit = 17 %
Sp of car = Rs 50000
Cp = sp/1 + .profit percentage
Cp = 50000/1+.17
Cp= 50000/1.17= Rs 42735.04
Now he wants to sell at Rs 47000
New sp = Rs 47000
Profit sp-cp = 47000-42735.04 = Rs 4264.96
Profit % = profitx100/cp
Profit % = 4264.96×100/42735.04 = 9.98 %
New profit % = 9.98
___________________________________________
Solution by Vicky :
total sold price with 17% profit =50,000 (Including 17% profit)
now lets break this 50,000
50,000=X(original cost of car)+0.17x(17% profit) :- x is supposed cars original price
50,000=x+0.17x
x=50,000/1.17 (By taking x common)
x=42,735 (which is Original cost of car)
now again his is selling his damn car at Rs 47,000, that means his profit this time will be
47,000-42,735(original amount of car we just calculated above)=4265 (profit this time)
now calculate the percentage of this above calculated Profit with simple formula
4265/42735*100= 9.98% (Answer) cheers