Finding IRQ from standard deviation and normal distribution

#1
Here's my problem. Any help or insight would be greatly appreciated:

A report provided a standard deviation on waiting time to single room
occupancy hotels to be 12.9 days. Given that the waiting times follow a
Normal distribution, what is the IQR here (single number)?

Thanks in advance!!
 

Dason

Ambassador to the humans
#2
Sounds like homework. Oh well. So you're given the standard deviation. You don't know the mean but that doesn't matter so just assume it is 0 (do you see why it doesn't matter?)

Then you need to know what the IQR is. It's the difference between two numbers related to the distribution of interest. If you know the mean and the standard deviation can you calculate those two numbers?
 
#3
It is homework, I apologize if that is against forum rules.

I can find the IQR if I have the mean and standard deviation. However, I'm not now clear on how to obtain the mean. Why doesn't it matter? Does this relate to the fact that it's a normal distribution?

Thanks so much for your assistance, this problem had me totally baffled.
 

Dason

Ambassador to the humans
#4
Ok so you have the standard deviation. What happens if you assume the mean is 0 and you compute the IQR. What happens if you assume the mean is 200 and you compute the IQR? Do you get the same value?