Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
17 Mar 2019, 14:17
Kudos
Bookmarks
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
85%
(hard)
Question Stats:
57% (02:46) correct
43%
(02:35)
wrong
based on 222
sessions
History
Date
Time
Result
Not Attempted Yet
GMATH practice exercise (Quant Class 17)
There are many boxes in a certain room, and each box has a label attached to it in which the number of balls contained in that box is written. If there are exactly 612 balls in all boxes combined, and it is known that the numbers presented at the labels form a sequence of the first N consecutive positive multiples of 4, the value of N is:
(A) divisible by 3
(B) divisible by 7
(C) divisible by 11
(D) divisible by 13
(E) prime
There are many boxes in a certain room, and each box has a label attached to it in which the number of balls contained in that box is written. If there are exactly 612 balls in all boxes combined, and it is known that the numbers presented at the labels form a sequence of the first N consecutive positive multiples of 4, the value of N is:
(A) divisible by 3
(B) divisible by 7
(C) divisible by 11
(D) divisible by 13
(E) prime
17 Mar 2019, 17:57
Kudos
Bookmarks
fskilnik
\(4 \cdot 1 + 4 \cdot 2 + \ldots + 4 \cdot N = 612\)
\(? = N\,\,\,\,\left( {N \ge 1\,\,{\mathop{\rm int}} } \right)\,\,\,\left( * \right)\)
\(612 = 4(1 + 2 + \ldots + N)\,\,\,\mathop = \limits^{{\rm{Arith}}{\rm{.Seq}}} \,\,\,4\left[ {{{N\left( {N + 1} \right)} \over 2}} \right]\,\, = \,\,2N\left( {N + 1} \right)\)
\(N\left( {N + 1} \right) = 306 = 2 \cdot {3^2} \cdot 17\,\,\left[ { = 17 \cdot 18} \right]\,\,\,\,\,\mathop \Rightarrow \limits^{\left( * \right)} \,\,\,\,\,N = 17\)
The correct answer is (E).
We follow the notations and rationale taught in the GMATH method.
Regards,
Fabio.
General Discussion
15 Apr 2025, 22:54
Kudos
Bookmarks
we can also use Sum of aP: N/2(2A +(N-1)D) here A=4 and D=4
