msmith8754 wrote:If each pencil was either 23cents or 21 cents, how many 23 cents pencils were purchased?
(1) 6 pencils were bought
(2)Total value of pencils bought was 130 cents
I am stumped with this one . Thank you in advance for your feedback.
Statement 1: 6 pencils were bought
No way to determine how many of the 6 pencils cost 23 cents.
Insufficient.
Statement 2: Total value = 130 cents
Since 6*23 = 138, we know that the number of 23 cent pencils was less than 6.
Let's try buying 5 or fewer 23 cent pencils to see whether the remaining amount could be purchased with the 21 cent pencils:
5*23 = 115. 130-115 = 15. 15 is not divisible by 21.
4*23 = 92. 130-92 = 38. 38 is not divisible by 21.
3*23 = 69. 130-69 = 61. 61 is not divisible by 21.
2*23 = 46. 130-46 = 84. 84/21 = 4. We could buy two 23 cent pencils and four 21 cent pencils.
1*23 = 23. 130-23 = 107. 107 is not divisible by 21.
Since the only viable combination requires that two 23 cent pencils be purchased, sufficient.
The correct answer is
B.
This question involves a common GMAT trick. When a DS problem is restricted to positive integers -- we can't buy 1/2 a pencil or -3 pencils -- one equation might be sufficient information to solve for 2 variables. Be careful!
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
