I need a push in the right direction, not sure how to attack the problems..

#1
Hi :)
I am new here on the forum and find it a bit difficult to learn the way to go at different statistics/probability - problems.

For the most times I am able to figure it out myself doing some research, but the last two problems has got me stuck for a few days.
I would be really thankful for any tip as how to adress the problem correct, so that I can try and find the solution myself.

Okay here is the first case:

- In one age-group of skiing in a ski-race we assume that the end time X (in minutes) is the normal distributed with the expectancy of 290 and a standard deviation of 27. What is the probability for one skier in this age-group will use more than 300 minutes (5 hours)?

comment: Not sure how to adress this problem, thought I am told to use a chart for cumulative standardized normal distribution table.
I am not sure how to adress normal distribution problems in general.



The second case:
- A shopping-center have an average visit per minute of 23 new costumers. Use normal distribution, with and without whole-number-correction to find the probability for that in t=14 minutes there will come at least 336 costumers to the shopping-center.

comment: Not sure how to adress normal distribution problems.


If there is anyone who would help me get started, I would be very grateful!

Thanks!
 

hlsmith

Not a robit
#2
Wording a little different on first problem, but how many stdev is 300 from 290? What can you do with that number (n udge, use a table). Been awhile since I have done these problem so hopefully some one chimes in if I missed something.
 
#3
Wording a little different on first problem, but how many stdev is 300 from 290? What can you do with that number (n udge, use a table). Been awhile since I have done these problem so hopefully some one chimes in if I missed something.
Thanks for the reply! :)
I will try to take this in to consideration while trying to solve it, but I am not all sure what to do...

My problems are duo till tomorrow, I'm hoping I will get them right by then :)