permutation or combination?

[tohellandback]

A second grade class is writing reports on birds. The students' teacher has given them a list of four birds they can choose to write about. If Lizzy wants to write a report that includes two or three of the birds, how many different reports can she write?

A. 64 B. 36 C. 12 D. 29

I am getting confused with these kind of questions
shouldn't we do it like this?
ways of chosing 2 birds=4c2=6
ways of chosing 3 birds=4c3=4

answer 6+4 =10 ways.

OA is B.[/spoiler]

[rahulg83]

If order matters ie B1 B2 is different from B2 B1, then answer could be calculated as 4C2 * 2! + 4C3 * 3! = 36

But this is the ambiguity here. If order doesn't matter your answer is right.

I have searched for this question, found one link, please check

https://www.beatthegmat.com/combinations ... t9478.html

[scoobydooby]

the link that rahulg83 sent has 6 birds, if its a typo, your solution is correct tohellandback!

[rahulg83]

scooby, but the logic remains same...

we don't know whether order is important here or not. I looked into one more forum https://gmat.learnhub.com/lesson/2207-gm ... problems-i and there the solution which was given considers order important.

[scoobydooby]

right rahulg, the question is ambiguous indeed. they assumed order matters

[Stuart@KaplanGMAT]

A second grade class is writing reports on birds. The students' teacher has given them a list of four birds they can choose to write about. If Lizzy wants to write a report that includes two or three of the birds, how many different reports can she write?

A. 64 B. 36 C. 12 D. 29

I am getting confused with these kind of questions
shouldn't we do it like this?
ways of chosing 2 birds=4c2=6
ways of chosing 3 birds=4c3=4

answer 6+4 =10 ways.

OA is B.[/spoiler]

Nothing in the question suggests that order matters - what's the source?

Whenever you question a problem's validity, please include the source of the problem.

[Ian Stewart]

A second grade class is writing reports on birds. The students' teacher has given them a list of four birds they can choose to write about. If Lizzy wants to write a report that includes two or three of the birds, how many different reports can she write?

I've commented on this problem elsewhere, but the wording is terrible. The question asks how many different reports she can write; well clearly she can write a nearly infinite number of different reports even after choosing what birds to write about. The question means to ask how many different selections of birds she could make, and it isn't clear if the order should matter: will the report be in chapters, one about each bird, and will a different sequence of chapters make one report different from another? Or are we only being asked how many different sets of birds she could choose? In any case, the question is ambiguous, and no real GMAT counting question is ever unclear about whether order matters, so this question is not worth spending any time on.