• e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • examPAL
    Most awarded test prep in the world
    Now free for 30 days

    Available with Beat the GMAT members only code

    MORE DETAILS
    examPAL

OG 13 30

This topic has 3 expert replies and 0 member replies
oquiella Master | Next Rank: 500 Posts Default Avatar
Joined
12 May 2015
Posted:
164 messages
Upvotes:
3

OG 13 30

Post Thu Dec 24, 2015 9:37 am
The only gift certificates that a certain store sold yesterday were worth either $100 each or $10 each. If the store sold a total of 20 gift certificates yesterday. how many gift certificates worth $10 each did the store sell yesterday?


1. The gift certificates sold by the store yesterday were worth a total of between $1650 and $1800.
2. Yesterday the store sold more than 15 gift certificates worth $100 each.

Answer: A


Please explain why A is sufficient when there could have been a range between $1650 and $1800.

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Post Sun Feb 18, 2018 8:32 pm
Hi All,

We're told that the only gift certificates that a certain store sold yesterday were worth either $100 each or $10 each and the store sold a total of 20 gift certificates yesterday. We're asked for the number of gift certificates worth $10 each that the store sold yesterday. This question can be solved with a bit of 'brute force' and some basic arithmetic.

To start, since we have just 20 gift certificates, we can list out a few of the possibilities and look for a pattern.
There could be...
20 $10 certificates and 0 $100 certificates = (20)($10) + (0)($100) = $200
19 $10 certificates and 1 $100 certificates = (19)($10) + (1)($100) = $290
18 $10 certificates and 2 $100 certificates = (18)($10) + (2)($100) = $380
17 $10 certificates and 3 $100 certificates = (17)($10) + (3)($100) = $470

For every $10 certificate that is changed to a $100 certificate, the total value of the 20 certificates increases by $90 (and you can use this pattern to go 'in reverse' from 20 $100 certificates on down).

1) The gift certificates sold by the store yesterday were worth a total of between $1650 and $1800.

Based on the pattern defined above, the total could be...
$2000, $1910, $1820, $1730, $1640, etc.

Only one of these values is between $1650 and $1800 though - $1730 (3 $10s and 17 $100s).
Fact 1 is SUFFICIENT

2. Yesterday the store sold more than 15 gift certificates worth $100 each.

With Fact 2, there are several possible outcomes, including $2000 (0 $10s and 20 $100s) and $1920 (1 $10 and 19 $100s).
Fact 2 is INSUFFICIENT

Final Answer: A

GMAT assassins aren't born, they're made,
Rich

_________________
Contact Rich at Rich.C@empowergmat.com

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Post Fri Dec 25, 2015 7:04 am
oquiella wrote:
The only gift certificates that a certain store sold yesterday were worth either $100 each or $10 each. If the store sold a total of 20 gift certificates yesterday. how many gift certificates worth $10 each did the store sell yesterday?


1. The gift certificates sold by the store yesterday were worth a total of between $1650 and $1800.
2. Yesterday the store sold more than 15 gift certificates worth $100 each.

Answer: A


Please explain why A is sufficient when there could have been a range between $1650 and $1800.
Algebraically, we can say that 'x' is the number of $10 certificates and '20-x' is the number of $100 certificates. (Because we know there are 20 total.) We know that 10x + 100(20-x) is the total value of the certificates. 10x + 100(20-x) = 10x + 2000 - 100x = 2000 - 90x. We know this value is between 1650 and 1800. Now test x's.

x = 1 --> 2000 - 90 = 1910. Nope
x = 2 --> 2000 - 180 = 1820. Nope
x=3 ---> 2000 - 270 = 1730. Satisfies!
x = 4 ---> 2000 - 360 = 1640. Nope

Only one value works, so we know that x = 3.

_________________
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course

  • +1 Upvote Post
  • Quote
  • Flag
Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now!

GMAT/MBA Expert

Post Fri Dec 25, 2015 6:57 am
oquiella wrote:
The only gift certificates that a certain store sold yesterday were worth either $100 each or $10 each. If the store sold a total of 20 gift certificates yesterday. how many gift certificates worth $10 each did the store sell yesterday?


1. The gift certificates sold by the store yesterday were worth a total of between $1650 and $1800.
2. Yesterday the store sold more than 15 gift certificates worth $100 each.

Answer: A


Please explain why A is sufficient when there could have been a range between $1650 and $1800.
The key here is to recognize that we have a total of 20 gift certificates and that the number of gift certificates of each type must be an integer value. Say the store sold 17 of $100 certificates and 3 of the $10. That would give us 17*100 + 3*10 = 1730. That's between 1650 and 1800, so that's one possible scenario.

Now let's see if anything else can work. What if there were 18 of the $100 certificates and 2 of the $10? That gives us a total of 1820 -not between 1650 and 1820 so this not a possibility that satisfies the statement.

What if there were 16 of the $100 certificates and 4 of the $10? That gives us a total of 1640 - not between 1650 and 1800, so we can't use this scenario either.

The only possibility that satisfies the statement is that there were 17 of the $100 certificates and 3 of the $10 certificates. So the answer is
A

_________________
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course

  • +1 Upvote Post
  • Quote
  • Flag
Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now!

Best Conversation Starters

1 lheiannie07 112 topics
2 ardz24 71 topics
3 Roland2rule 69 topics
4 LUANDATO 53 topics
5 swerve 45 topics
See More Top Beat The GMAT Members...

Most Active Experts

1 image description GMATGuruNY

The Princeton Review Teacher

154 posts
2 image description Rich.C@EMPOWERgma...

EMPOWERgmat

107 posts
3 image description Jeff@TargetTestPrep

Target Test Prep

106 posts
4 image description Scott@TargetTestPrep

Target Test Prep

98 posts
5 image description EconomistGMATTutor

The Economist GMAT Tutor

91 posts
See More Top Beat The GMAT Experts