Last visit was: 23 Nov 2024, 08:34 It is currently 23 Nov 2024, 08:34

Close

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

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GRE score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel
Verbal Expert
Joined: 18 Apr 2015
Posts: 30010
Own Kudos [?]: 36363 [1]
Given Kudos: 25927
Send PM
avatar
Intern
Intern
Joined: 08 Apr 2018
Posts: 44
Own Kudos [?]: 20 [0]
Given Kudos: 0
Send PM
Retired Moderator
Joined: 07 Jan 2018
Posts: 739
Own Kudos [?]: 1448 [0]
Given Kudos: 93
Send PM
avatar
Manager
Manager
Joined: 02 Dec 2018
Posts: 74
Own Kudos [?]: 31 [0]
Given Kudos: 0
Send PM
Re: A student's score on the final test in a certain course was [#permalink]
Please remove double post.

Originally posted by QuantumWonder on 17 Dec 2018, 10:10.
Last edited by QuantumWonder on 17 Dec 2018, 10:13, edited 1 time in total.
avatar
Manager
Manager
Joined: 02 Dec 2018
Posts: 74
Own Kudos [?]: 31 [0]
Given Kudos: 0
Send PM
Re: A student's score on the final test in a certain course was [#permalink]
Carcass wrote:
A student's score on the final test in a certain course was 60% greater than the average (arithmetic mean) score of the 2 other tests the student took in the course. The student's score on the final test was what percent of the student's average test score for the entire course?

A. \(33 \frac{1}{3} %\)

B. \(40%\)

C. \(75%\)

D. \(133 \frac{1}{3}%\)

E. \(160%\)


student's final test score: x1
avg of 2 other tests: (x2+x3)/2

The student's score on the final test was what percent of the student's average test score for the entire course?

x1/(avg of 3 tests)
.8(x2 + x3)
----------
.6(x2 + x3)

= 1.33 = 133%

x1 = 1.6 (x2+x3)/2
x1 = .8(x2+ x3)

the average of all three tests: (x1 + x2 + x3)/3
.8(x2 + x3) + x2 + x3
----------------------
3

1.8(x2 + x3)
-------------
3

= .6(x2 + x3)

The student's score on the final test was what percent of the student's average test score for the entire course?

Well you get that by dividing student's final score to the total average

.8(x2+x3)
----------
.6(x2 + x3)

= 130%
avatar
Manager
Manager
Joined: 02 Dec 2018
Posts: 74
Own Kudos [?]: 31 [0]
Given Kudos: 0
Send PM
Re: A student's score on the final test in a certain course was [#permalink]
amorphous wrote:
We can assume two values for score in the first and second test.
To make calculation simple Let us say the student's score in the first test was 50 and in the second test was also 50.
The average of the two test would be 50.
The question mentions that the student's score on the final test was 60% more than the average of the two tests.
Hence the final test score of the student was 50 * 1.6 = 80

Now we need to find the average of the three tests because we have to compare this with the final test score.
Avg of the three tests = \(\frac{50 + 50 + 80}{3}\) = \(\frac{180}{3}\) = 60
We have all the information needed to answer the question.
Therefore final score/avg of three scores * 100 = the final score as a % of avg of the three scores.
\(\frac{80}{60}\) * \(100\) = \(133.33%\)


My question is, when do you know when it is safe to plug in numbers? It wasn't obvious to me that it would have been safe to plug in numbers for this problem without changing the answer.
Retired Moderator
Joined: 07 Jan 2018
Posts: 739
Own Kudos [?]: 1448 [0]
Given Kudos: 93
Send PM
Re: A student's score on the final test in a certain course was [#permalink]
1
QuantumWonder wrote:
amorphous wrote:
We can assume two values for score in the first and second test.
To make calculation simple Let us say the student's score in the first test was 50 and in the second test was also 50.
The average of the two test would be 50.
The question mentions that the student's score on the final test was 60% more than the average of the two tests.
Hence the final test score of the student was 50 * 1.6 = 80

Now we need to find the average of the three tests because we have to compare this with the final test score.
Avg of the three tests = \(\frac{50 + 50 + 80}{3}\) = \(\frac{180}{3}\) = 60
We have all the information needed to answer the question.
Therefore final score/avg of three scores * 100 = the final score as a % of avg of the three scores.
\(\frac{80}{60}\) * \(100\) = \(133.33%\)


My question is, when do you know when it is safe to plug in numbers? It wasn't obvious to me that it would have been safe to plug in numbers for this problem without changing the answer.



When the ans required is in percent then try to work with numbers because we would be comparing in relative basis rather than absolute value.
User avatar
GRE Prep Club Legend
GRE Prep Club Legend
Joined: 07 Jan 2021
Posts: 5042
Own Kudos [?]: 74 [0]
Given Kudos: 0
Send PM
Re: A student's score on the final test in a certain course was [#permalink]
Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Prep Club for GRE Bot
Re: A student's score on the final test in a certain course was [#permalink]
Moderators:
GRE Instructor
84 posts
GRE Forum Moderator
37 posts
Moderator
1111 posts
GRE Instructor
234 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne