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.
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
31 May 2008, 04:30
Kudos
Bookmarks
1. A box contains 100 balls each numbered 1 to 100. 3 balls are picked in random with replacement - what is the probability that the sum is Odd?
1. 1/4
2. 3/8
3. 1/2
4. 5/8
5. 3/4
OA= 1/2
How can this be right?? The solution has ignored one possiblity where in case of Odd, Even, Even (all 3 ways) when both the even numbers are the same - this makes a double count what say?
Same is the case with Odd, odd, odd combo!
1. 1/4
2. 3/8
3. 1/2
4. 5/8
5. 3/4
OA= 1/2
How can this be right?? The solution has ignored one possiblity where in case of Odd, Even, Even (all 3 ways) when both the even numbers are the same - this makes a double count what say?
Same is the case with Odd, odd, odd combo!
Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
31 May 2008, 05:06
Kudos
Bookmarks
Answer Has to be 1/2.
Explanation 1: There is equal number of odd number and equal number of even number. As there is no bias to any of them, so chances of obtaining sum of odd or sum of even has to be equally likely events and hence they will each have probability = 1/2.
Explanation 2:
Odd sum can be obtained in 2 ways = odd + odd + odd or Even + Even + Odd
Number of even numbers = 50
Number of odd numbers = 50
Probability = 50c3/100c3 + 50c2*50c1/100c3 = 1/2
Explanation 1: There is equal number of odd number and equal number of even number. As there is no bias to any of them, so chances of obtaining sum of odd or sum of even has to be equally likely events and hence they will each have probability = 1/2.
Explanation 2:
Odd sum can be obtained in 2 ways = odd + odd + odd or Even + Even + Odd
Number of even numbers = 50
Number of odd numbers = 50
Probability = 50c3/100c3 + 50c2*50c1/100c3 = 1/2
31 May 2008, 12:25
Kudos
Bookmarks
To produce odd addition:
odd + even + even => P = 1/2 * 1/2 * 1/2 = 1/8
even + odd + even => P = 1/8
even + even + odd => P = 1/8
odd + odd + odd => P = 1/8
1/8 * 4 = 1/2
odd + even + even => P = 1/2 * 1/2 * 1/2 = 1/8
even + odd + even => P = 1/8
even + even + odd => P = 1/8
odd + odd + odd => P = 1/8
1/8 * 4 = 1/2
