GMATPill wrote:
For anyone struggling to understand combinatorics and how this concept may show up on the exam, please learn these critical insights:
It is broken down as follows:
00:00 - Intro
01:00 - Warmup
02:12 - Part 1 Overview: Combinations & Permutations vs Variations
08:35 - Part 1 Details: Picking Teams, Dice, Pocket Pair, Dating
17:21 - Part 2: Apply to GMAT - Word Problem #1
22:13 - Part 2: Apply to GMAT - Word Problem #2
31:34 - Part 2: Apply to GMAT - Word Problem #3
38:04 - Part 3: Poker Probability - Pocket Pair vs Pocket Aces
43:40 - Part 3: Poker Probability - Given Pocket Aces, 3-of-a-Kind?
46:13 - Part 3: Poker Probability - 1-Pair by 5th Flop
49:59 - Part 3: Poker Probability - Full House/Flush
1:00:00 - Conclusion
Note: the Poker part is just for fun - you will not see poker questions on the test. But the prior 3 examples are game for the test.
I am stuck with 3 problems and the way they are solved:
1. How many distinct ways can 3 guys vote for those 3 girls? (variations)
Solved by considering the 1st guy can date 3 girls, 2nd guy can date 3 girls as well ...
3*3*3 = 3^3
2. How many potential dates can happen between 3 guys and 3 girls? (combinations)
3c1 + 3c1 + 3c1 = 9
3. How many different ways can 3 guys and 3 girls pair up for a group date of 6 people? (permutations)
3c1 * 2c1 *1c1 = 6
Can someone please help me understand what is the difference between the 3, as it is all about 3 guys choosing 3 girls, and why different methods are used