Can anyone clarify my doubts regarding this problem I came across in the Quant Problem area on website

GRE Quant Problem Solving
1

In a class containing k students, the teacher calculated the students’ mean grade on a test to be 50. Unfortunately, the teacher made a mistake in the calculation and recorded one student’s score of 20 as 70. If the mean after the error was fixed is one more than the number of students in the class, what is k?

The problem can be found in Data Analysis category. Earlier when I solved the question I formed a wrong equation by interchanging 20 and 70, I got 50 as answer which was correct as per website. But when I was doing it again, I formed the correct equation (as per my judgement) it became a very complicated equation and the solutions were not whole numbers. Can anyone shed some light on this question?

2

The equation is \frac{50k + 50}{k} = k + 1. k should be 50.

3

In a class containing k students, the teacher calculated the students’ mean grade on a test to be 50. Unfortunately, the teacher made a mistake in the calculation and recorded one student’s score of 20 as 70. If the mean after the error was fixed is one more than the number of students in the class, what is k?

4

I think there was a possible ambiguity in that question which has been fixed - can you check again?

5

Yes, it has been fixed. Thanks a lot :blush:

6

wait i’m confused so did the teacher mark it down as 70 or as 20?

7

See https://www.gregmat.com/problems/problem/in-a-class-with-k-students/

1 Like
8

Hey, I agree with you on that
that gives us
50k+

9

This link doesn’t work.

10

Try this.