BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

700+ level

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 152
Joined: Fri Apr 24, 2015 1:39 am
Location: Rourkela Odisha India
Thanked: 2 times
Followed by:3 members
GMAT Score:650

700+ level

by akash singhal » Tue Nov 17, 2015 4:57 am
If Bob produces 36 or fewer in a week, he is paid X dollars per item. If Bob produces more than 36 items, he
is paid X dollars per item for the first 36 items, and 3/2 times that amount for each additional item. How
many items did Bob produce last week?

(1) Last week Bob was paid total of $480 for the items that he produced that week.
(2) This week produced 2 items more than last week and was paid a total of $510 for the item that he
produced this week.

OE E

Please Explain How!!!
Top
Source: — Data Sufficiency |
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Tue Nov 17, 2015 5:15 am
akash singhal wrote:If Bob produces 36 or fewer in a week, he is paid X dollars per item. If Bob produces more than 36 items, he is paid X dollars per item for the first 36 items, and 3/2 times that amount for each additional item. How many items did Bob produce last week?

(1) Last week Bob was paid total of $480 for the items that he produced that week.
(2) This week produced 2 items more than last week and was paid a total of $510 for the item that he
produced this week.
Statements combined:
(this week's earnings) - (last week's earnings) = 510 - 480 = $30.
Implication:
The 2 additional items produced this week each account for an additional $15 in earnings, for a total earnings increase of $30.

Case 1: x=15
In this case:
Number of items produced last week = 480/15 = 32.
Number of items produced this week = 510/15 = 34.

Case 2: (3/2)x = 15, implying that x=10
Last week:
Total earnings for the first 36 items = 36*10 = 360.
Earnings paid at $15 per item = 480-360 = 120.
Number of items paid at $15 per item = 120/15 = 8.
Total items = 36+8 = 44.

This week:
Total earnings for the first 36 items = 36*10 = 360.
Earnings paid at $15 per item = 510-360 = 150.
Number of items paid at $15 per item = 150/15 = 10.
Total items = 36+10 = 46.

Since the total number of items produced last week is 32 in Case 1 but 44 in Case 2, INSUFFICIENT.

The correct answer is E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

by Max@Math Revolution » Sat Nov 21, 2015 9:16 am
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

If Bob produces 36 or fewer in a week, he is paid X dollars per item. If Bob produces more than 36 items, he
is paid X dollars per item for the first 36 items, and 3/2 times that amount for each additional item. How
many items did Bob produce last week?

(1) Last week Bob was paid total of $480 for the items that he produced that week.
(2) This week produced 2 items more than last week and was paid a total of $510 for the item that he
produced this week.

This is a '2by2' question which can give a table as below:
Image

There are 3 variables (m,n,x) and 2 equations are given by the 2 conditions, giving high chance (E) will be our answer
Even if we combine the 2 conditions, we cannot obtain unique value for m, so the answer becomes (E).

For cases where we need 3 more equation, such as original conditions with "3 variables", or "4 variables and 1 equation", or "5 variables and 2 equations", we have 1 equation each in both 1) and 2). Therefore, there is 80% chance that E is the answer (especially about 90% of 2 by 2 questions where there are more than 3 variables), while C has 15% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since E is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, C or D.
Top
Post new topic Post Reply
• Page 1 of 1