GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 10 Dec 2018, 05:09

Close

GMAT 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 GMAT 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
Events & Promotions in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
  • Free lesson on number properties

     December 10, 2018

     December 10, 2018

     10:00 PM PST

     11:00 PM PST

    Practice the one most important Quant section - Integer properties, and rapidly improve your skills.
  • Free GMAT Prep Hour

     December 11, 2018

     December 11, 2018

     09:00 PM EST

     10:00 PM EST

    Strategies and techniques for approaching featured GMAT topics. December 11 at 9 PM EST.

If Janice was 25 years old z years ago and Lisa will be 23 years old

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 51067
If Janice was 25 years old z years ago and Lisa will be 23 years old  [#permalink]

Show Tags

New post 04 Jan 2018, 22:47
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

79% (02:02) correct 21% (02:17) wrong based on 48 sessions

HideShow timer Statistics

If Janice was 25 years old z years ago and Lisa will be 23 years old in p years, what was the average (arithmetic mean) of their ages 5 years ago?

A. (48 + z - p)/2
B. (38 - z + p)/2
C. (38 + z + p)/2
D. (38 + z - p)/2
E. (48 + z + p)/2

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 51067
Re: If Janice was 25 years old z years ago and Lisa will be 23 years old  [#permalink]

Show Tags

New post 04 Jan 2018, 22:48
Bunuel wrote:
If Janice was 25 years old z years ago and Lisa will be 23 years old in p years, what was the average (arithmetic mean) of their ages 5 years ago?

A. (48 + z - p)/2
B. (38 - z + p)/2
C. (38 + z + p)/2
D. (38 + z - p)/2
E. (48 + z + p)/2


Check other Age Problems in our Special Questions Directory.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Senior SC Moderator
avatar
V
Joined: 22 May 2016
Posts: 2197
Premium Member CAT Tests
If Janice was 25 years old z years ago and Lisa will be 23 years old  [#permalink]

Show Tags

New post 05 Jan 2018, 15:35
1
Bunuel wrote:
If Janice was 25 years old z years ago and Lisa will be 23 years old in p years, what was the average (arithmetic mean) of their ages 5 years ago?

A. (48 + z - p)/2
B. (38 - z + p)/2
C. (38 + z + p)/2
D. (38 + z - p)/2
E. (48 + z + p)/2

Assign values that make the equations easy.
Let Janice = 30 now, z years ago she was 25
z = 5
Let Lisa = 20 now, in p years she will be 23
p = 3

Average of their ages 5 years ago? Five years ago
Janice: (30 - 5) = 25
Lisa: (20 - 5) = 15
Average 5 yrs ago \(\frac{25+15}{2}=20\)

All the answers are divided by 2.
With z = 5, p = 3, find the answer with a numerator of 40, because 40/2 = 20 = average of their ages


A. (48 + z - p)/2
48 + 5 - 3 = 50 NOT A MATCH

B. (38 - z + p)/2
38 - 5 + 3 = 36 NOT A MATCH

C. (38 + z + p)/2
38 + 5 + 3 = 46 NOT A MATCH

D. (38 + z - p)/2
38 + 5 - 3 = 40 MATCH

E. (48 + z + p)/2
48 + 5 + 3 = 56 NOT A MATCH

Answer
Intern
Intern
avatar
S
Joined: 12 Oct 2017
Posts: 40
Re: If Janice was 25 years old z years ago and Lisa will be 23 years old  [#permalink]

Show Tags

New post 05 Jan 2018, 19:05
If Janice was 25 years old z years ago => Janice's age now = 25 + z => 5years ago = 25+ z - 5
Lisa will be 23 years old in p years => Lisa's age now = 23 - p => 5 years ago = 23 - p - 5
Hence, the average (arithmetic mean) of their ages 5 years ago = (25+z-5 + 23-p -5)/2 = (38 + z - p)/2. the answer is D
-----
Please +1 kudos if the explanation is clear.
Thank you!
Manager
Manager
User avatar
G
Joined: 22 May 2015
Posts: 103
Re: If Janice was 25 years old z years ago and Lisa will be 23 years old  [#permalink]

Show Tags

New post 05 Jan 2018, 21:04
Straight forward classic algebra problem.

Assume present ages are j and p
Eq 1 : 25 = j-z
Eq 2 : 23 = l+p

Need to find avg of there ages 5 years ago ie (j-5+l-5) / 2 = (j+l-10)/2
substituting j and l from eq 1 and eq 2 we get the answer as D
_________________

Consistency is the Key

Manager
Manager
avatar
B
Joined: 23 Oct 2017
Posts: 64
Re: If Janice was 25 years old z years ago and Lisa will be 23 years old  [#permalink]

Show Tags

New post 06 Jan 2018, 04:40
Bunuel wrote:
If Janice was 25 years old z years ago and Lisa will be 23 years old in p years, what was the average (arithmetic mean) of their ages 5 years ago?

A. (48 + z - p)/2
B. (38 - z + p)/2
C. (38 + z + p)/2
D. (38 + z - p)/2
E. (48 + z + p)/2

------------
Janice's age z years ago = 25 years old, so as of now age of janice = 25 +z
Since Lisa will be 23 years old in p years, so as of now age of lisa = 23- p
Now average of both their 5 years beack will be:
(25+z-5 + 23-p -5)/2
= (38 + z - p)/2
GMAT Club Bot
Re: If Janice was 25 years old z years ago and Lisa will be 23 years old &nbs [#permalink] 06 Jan 2018, 04:40
Display posts from previous: Sort by

If Janice was 25 years old z years ago and Lisa will be 23 years old

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.