Standard Deviation without the data set

[chickenpie]

Hi, my question;

Mean time to reply to emails is 191 days

If 47.85% of replies were after 75 days but before 191, show that the std dev is 58..

I know how to calculate SD but the question is throwing me as no data set?

thanks in advance for any pointers

A

 

[Deleted member 4993]

Hi, my question;

Mean time to reply to emails is 191 days

If 47.85% of replies were after 75 days but before 191, show that the std dev is 58..

I know how to calculate SD but the question is throwing me as no data set?

thanks in advance for any pointers

A

Have you been taught z-transformation and z-distribution?

 

[chickenpie]

Have you been taught z-transformation and z-distribution?

No!

 

[Dr.Peterson]

Do you know anything about distributions, such as the normal distribution?

Is anything stated or implied about the distribution of the mean time to reply?

 

[Deleted member 4993]

No!

You'll have to learn about that (z-transform) to answer this question.

Start with studying:

http://www.statistics4u.info/fundstat_eng/ee_ztransform.html#:~:text=The z-transform is also,transformed sample is always zero.

 

[chickenpie]

yes some knowledge of normal distribution which I'm looking at now..

but nothing else implied about the mean time to reply