Help on Achiever QR question.

[Morena]

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Hi guys,
When looking at this question I'm not sure where to begin. What information is meaningful and what is irrelevant. When I looked at the answer it seemed really easy but I still don't understand the question. Can anyone help me interpret it in a different way. Maybe with colored marbles or something?
Here is the question. Any help would be appreciated. 🙂

Achiever 3 QR question 5

The best colleague working only 2 days a week has already scheduled to have her lunch at 2 designated restaurants of the five eating places near your office. If you work 5 days a week, how many ways can you schedule your restaurant visits so that you and your colleague can always have lunch together?

 

[herkulease]

this problem came up a while back and it took me a while to see it.

I still disagree with its wording though.

the key her is that you only have 3 days to choose from. since the other 2 days you are already eating with your friend. These are specific days so you know order matters.

since she already picked 2 places this also leaves you with 3 restaurants to choose from.

So it becomes 3 Choose 3.

so its

3!
-------
(3-3)!

or

3! which is 6. 0! = 1.

so 6 ways

where I disagree is that no where does it say you can't visit the the same restaurant everyday on your 3 days. Nor does it say that the 2 restaurant your friend chooses is excluded from your list of choices. You're left to assume that.

 

[Morena]

yeah the wording is poor in this question. Thanks alot for your help tho. 🙂