The anagram approach in MGMAT guide .. when to use it?

[chengsaimun]

Hi ...

Struggling with perm/comb. How do I know when to use anagram approach and when not to? I am confused when [b]not[b] mot to do so, esp when it takes up more than 2 mins of my time in the exam...

Could the instructors illustrate it?

Thanks alot for your time.

[chengsaimun]

any one pls ?

[doclkk]

any one pls ?

Hi:

I'm not great

But here's a shot.

7 people board an airport shuttle with only 3 avail seats, how many DIFFERENT seating arrangements are possible?

The seats in the shuttle are considered different so this is a permutation question

If you anagram, it will be

XYZAAAA

So set of 7, you're picking 3. Order matters so this is a permutation because the seats are different. You see how order matters because XYZ.

7!
4!

You're only looking at the people sitting down on the seats. You don't care about the people standing up. So you want to CANCEL OUT the people standing up. They do not concern us.

When order doesn't matter think of it as

XXXAAAA

So here's 7! / 3!4!

So this example would be if there was that same shuttle, but how many different ways of 3 people being seated can you. Here order doesn't matter. So you see how you're canceling 3 X's and 4 A's?

Its a combination problem.

Honestly, I think the anagram method is actually more confusing than just understanding Combination / Permutations. =P

If this doesn't make sense, I will try to explain it again. But this concept took me forever to learn until someone just told me - dude, just memorize the formulas and you're set.

[chengsaimun]

hi, i just hope more ppl are as helpful as u are .. esp when we are talking abt mgmat's own training method ...

i find anagram methodd easy to understand, however i just need to noe when not to use it, as i noe it does not solve all problems ...

any one pls ?

Hi:

I'm not great

But here's a shot.

7 people board an airport shuttle with only 3 avail seats, how many DIFFERENT seating arrangements are possible?

The seats in the shuttle are considered different so this is a permutation question

If you anagram, it will be

XYZAAAA

So set of 7, you're picking 3. Order matters so this is a permutation because the seats are different. You see how order matters because XYZ.

7!
4!

You're only looking at the people sitting down on the seats. You don't care about the people standing up. So you want to CANCEL OUT the people standing up. They do not concern us.

When order doesn't matter think of it as

XXXAAAA

So here's 7! / 3!4!

So this example would be if there was that same shuttle, but how many different ways of 3 people being seated can you. Here order doesn't matter. So you see how you're canceling 3 X's and 4 A's?

Its a combination problem.

Honestly, I think the anagram method is actually more confusing than just understanding Combination / Permutations. =P

If this doesn't make sense, I will try to explain it again. But this concept took me forever to learn until someone just told me - dude, just memorize the formulas and you're set.

[Ben Ku]

Thanks doclkk. Your illustrations were on target to illustrate the anagram method.

Many students who went through high school math freak out whenever there's a combination or permutation question. They remember perhaps scary formulas, and the confusion of when to use which. The beauty of MGMAT's anagram method is that you don't need to remember formulas or understand combinations or permutations. It works for any situation.

However, if you're more comfortable with the formulas, then by all means, stick with them. I know for me, it took me awhile to use the anagram method when the formulas were more convenient.

[chengsaimun]

Hi ..thanks for that ... but my question is really, when not to use anagram grid ... i believe there will be cases when it's really a pain to use ...

e.g. refering to this problem combination-manhattan-cat-5-problem-31-t3037.html .

it cannot be used (or rather it's a pain to use).

may i now how to recognize or identify a pattern so that i would be better off using other method.

thanks

[Ben Ku]

The anagram grid method should NOT be used in the example you refer to, because
(1) It can be approached better as a counting problem instead of a combination/permutations question.
(2) There are restrictions in how things can be placed. The anagram grid should be used when there are no restrictions.

For example, if the license plate consists of, in this order, three unique letters followed by three unique digits, then the number of different license plates that can be generated is 26 * 25 * 24 * 10 * 9 * 8.

We would not use an anagram grid here because there are restrictions of what value can go in each spot. We are multiplying choices here by applying the Fundamental Theorem of Counting. Hope that helps.