how do i find mean and standard deviation

[perculathepv]

the paper says i have 860 short films. the lengths are normally distributed with 250 of them being under 5 minutes & 350 of them being under 7. i can’t wrap my head around any of it

 

[Deleted member 4993]

the paper says i have 860 short films. the lengths are normally distributed with 250 of them being under 5 minutes & 350 of them being under 7. i can’t wrap my head around any of it

Please post the EXACT problem, preferably a photocopy.

 

[perculathepv]

Please post the EXACT problem, preferably a photocopy.

i’ll write it out verbatim

In 2019 Jessica watched a total of 860 short films. The lengths of these films are also normally distributed with 250 of them being under 5 minutes in length and 350 of them being over 7 minutes in length.

Calculate the mean and standard deviation of Jessica’s film lengths - in minutes.

 

[Deleted member 4993]

i’ll write it out verbatim

In 2019 Jessica watched a total of 860 short films. The lengths of these films are also normally distributed with 250 of them being under 5 minutes in length and 350 of them being over 7 minutes in length.

Calculate the mean and standard deviation of Jessica’s film lengths - in minutes.

What have you learned about areas under normal distribution curve? Did you learn about z-transformation? What does your textbook/class notes say?

 

[perculathepv]

What have you learned about areas under normal distribution curve? Did you learn about z-transformation? What does your textbook/class notes say?

no we didn’t learn much about that. we also have had a lot of time in and out of covid lockdowns so it’s been hard

 

[Harry_the_cat]

What % are under 5 minutes?
What % are over 7 minutes?

Can you illustrate that on a diagram of a normal curve?