# In a class of 51 students, the difference between the highest mark and the least mark is 70.

1 vote
4.4k views

In a class of 51 students, the difference between the highest mark and the least mark is 70. If the average score is calculated without considering the student who got the highest mark, then the average score decreases by 1%. If the average score is calculated without considering the student who got the least mark, then the average score increases by 1.33%. What is the original average score of the class?

1. 60
2. 70
3. 80
4. 40

## 3 Answers

2 votes

Best answer
Let the average mark be x.

Total marks = 51x

50 * 0.99x = 51x - max

50 * 1.0133x = 51x - min

Subtracting last two,

50* 0.0233x = max - min = 70,

x = 60
8.3k points 55 131 178
selected
0 votes
let say t= total marks (addition of all the marks).

here we have given 51 students (n=51)

let say the average is x.

so according to the standard formula of finding the average   t/n=x

t=51x.

now, we can use any of the conditions

according to case one:

t-90/(51-1)=x-0.01x

now take t=51x and solve it

51x-90/(50)=0.99x

x=60.

here we get the same answer from the case 2 as well.

Answer : x=60.
74 points 2 5 6
0 votes
1.60
410 points 2 4

## Related questions

5 votes
2 answers
1
11.4k views
There are 150 students in a class. The number of students who play Cricket, Hockey, and Basketball are 125, 130, 135 respectively. If 5 students do not play any of the three games, the number of students playing all the three games must be at least 90 95 100 105
3 votes
1 answer
2
15.0k views
A alone can do a piece of work in 6 days and B alone in 8 days. A and B undertook to do it for Rs. 3200. With the help of C, they completed the work in 3 days. How much is to be paid to C? A. Rs. 375 B. Rs. 400 C. Rs. 600 D. Rs. 800
2 votes
2 answers
3
1.7k views
What was the percentage increase in the price of oil between 1998 and 2006? 4.83% 48.3% 51.3% 4.13% 5.13% If the total oil supply had grown at the same rate as the former USSR oil supply between 2000 and 2006 how much would this have exceeded the ... was the largest combined change in supply from the previous year for OPEC, the former USSR and other Non-OECD countries? 2000 2003 2004 2005 2006
2 votes
2 answers
4
19.8k views
What is the least number of cuts required to cut a cube into 84 identical pieces, assuming all cuts are made parallel to the faces of the cube? 11 12 13 10
2 votes
2 answers
5
636 views
In the given figure, $∠BAC = 120º$ and $AD$ is the bisector of $∠BAC$. If $\frac{(AD)(AB)}{BD} = \frac{AE}{EC}( AE + EC )$ and $∠EDC = ∠ECD$, what is the ratio of $∠B$ and $∠C$? 1 : 1 1 : 2 2 : 3 5 : 6