GRE Prep Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
The average (arithmetic mean) score of x students on a certain exam is
[#permalink]
12 Aug 2021, 07:26
12 Aug 2021, 07:26
Expert Reply
00:00
Question Stats:
92% (01:19) correct
7% (00:53) wrong based on 13 sessions
Hide Show timer Statistics
The average (arithmetic mean) score of x students on a certain exam is 81. If one additional student takes the exam and scores a 99, the average score will increase to 83. What is the value of x ?
(A) 7
(B) 8
(C) 9
(D) 10
(E) 11
(A) 7
(B) 8
(C) 9
(D) 10
(E) 11
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: The average (arithmetic mean) score of x students on a certain exam is
[#permalink]
12 Aug 2021, 07:38
12 Aug 2021, 07:38
Carcass wrote:
The average (arithmetic mean) score of x students on a certain exam is 81. If one additional student takes the exam and scores a 99, the average score will increase to 83. What is the value of x ?
(A) 7
(B) 8
(C) 9
(D) 10
(E) 11
(A) 7
(B) 8
(C) 9
(D) 10
(E) 11
Let's plug in some "nice" values for the test results.
The average (arithmetic mean) score of x students on a certain exam is 81
So, one possibility is that EACH of those x students received a score of 81.
So, the TOTAL SUM of all x scores = 81x
If one additional student takes the exam and scores a 99, the average score will increase to 83. What is the value of x ?
With this additional score, we now have x + 1 scores
Also, the TOTAL SUM of all x +1 scores = 81x + 99
Since the new average is 83, we can write: (81x + 99)/(x + 1) = 83
Multiply both sides by (x+1) to get: 81x + 99 = 83(x + 1)
Expand: 81x + 99 = 83x + 83
Rearrange: 16 = 2x
Solve: x = 8
Answer: B
RELATED VIDEO
gmatclubot
Re: The average (arithmetic mean) score of x students on a certain exam is [#permalink]
12 Aug 2021, 07:38
Moderators:
