Tom owns movies on DVD and Blue-ray in a ratio of 7:2. If he buys 6 more Blue-ray movies, the ratio would change to 11:4. How many Blue ray movies did he have to start with?
Please show steps to answer this problem.
Ratios
This topic has expert replies
-
- Junior | Next Rank: 30 Posts
- Posts: 21
- Joined: Mon Aug 30, 2010 11:51 am
- ezhilkumarank
- Moderator
- Posts: 92
- Joined: Sat Feb 21, 2009 1:20 am
- Thanked: 5 times
- Followed by:1 members
Initial RatioSFtraveler wrote:Tom owns movies on DVD and Blue-ray in a ratio of 7:2. If he buys 6 more Blue-ray movies, the ratio would change to 11:4. How many Blue ray movies did he have to start with?
Please show steps to answer this problem.
DVD : BR
7x: 2x
Adding 6 more BR movies changes the ratio to 11:4.
Hence setting up the equation - (2x+6)/7x = 4/11
=> 22x + 66 = 28x
=> 6x = 66 => x =11
Hence the original number of BR movies was 22 and the final number is 28.
Moving this post to PS forum.
"The will-to-do achieves the deed, when the mind that wills is strong indeed"
-
- Legendary Member
- Posts: 1337
- Joined: Sat Dec 27, 2008 6:29 pm
- Thanked: 127 times
- Followed by:10 members
please move to PS sub-forum.ezhilkumarank wrote:Initial RatioSFtraveler wrote:Tom owns movies on DVD and Blue-ray in a ratio of 7:2. If he buys 6 more Blue-ray movies, the ratio would change to 11:4. How many Blue ray movies did he have to start with?
Please show steps to answer this problem.
DVD : BR
7x: 2x
Adding 6 more BR movies changes the ratio to 11:4.
Hence setting up the equation - (2x+6)/7x = 4/11
=> 22x + 66 = 28x
=> 6x = 66 => x =11
Hence the original number of BR movies was 22 and the final number is 28.
Moving this post to PS forum.
also to cut on time the same approach with couple of reductions -->
D/B=7/2 AND D/(B+6)=11/4
2D=7B AND 4D=11B+66 --> 2*7B=11B+66 --> B=22
- GMATGuruNY
- 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
Sneaky but efficient approach:SFtraveler wrote:Tom owns movies on DVD and Blue-ray in a ratio of 7:2. If he buys 6 more Blue-ray movies, the ratio would change to 11:4. How many Blue ray movies did he have to start with?
Please show steps to answer this problem.
Since the DVDs are represented by a 7 and an 11 in the two ratios, the number of DVDs must be a multiple of both 7 and 11.
Thus, it is likely that DVDs = 7*11 = 77.
Thus, Blu-rays = 2*11 = 22, giving us the required ratio of 77:22 = 7:2.
To confirm that these values are correct, the new number of Blu-rays = 22+6 = 28, and the new ratio = 77:28 = 11:4.
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
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