Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
A random variable X follows a normal distribution with mean 20. (standard deviation 5)
Find probability 14=<X=<26
 one year ago
 one year ago
A random variable X follows a normal distribution with mean 20. (standard deviation 5) Find probability 14=<X=<26
 one year ago
 one year ago

This Question is Closed

kropot72Best ResponseYou've already chosen the best response.1
Do you know how to work out the zscores for 14 and 26? \[z=\frac{X\mu}{\sigma}\]
 one year ago

nickersiaBest ResponseYou've already chosen the best response.0
Yes, but I'm not sure should I put 6 and 6 for z? That way I got 50 for x, which makes me no sense
 one year ago

kropot72Best ResponseYou've already chosen the best response.1
\[z _{1}=\frac{1420}{5}=?\] \[z _{2}=\frac{2620}{5}=?\]
 one year ago

nickersiaBest ResponseYou've already chosen the best response.0
I got 76.98% as an answer. z= 1.2 and 1.2 So, z score from beginning of the curve to the s.d. of 1.2 is 0.8849, which meas that on the right it's 0.1151 and same on the left, so it's 0.2302. 23.02% are lower than 14 and bigger that 26, so 76.98% is X. Am I right?
 one year ago

kropot72Best ResponseYou've already chosen the best response.1
A standard normal distribution table gives the following values for cumulative probability: z = 1.2 : p = 0.8849 z = 1.2 : p = 0.1151 You can check these results on the table at the following link (choose 'normal.pdf' from the menu: http://www.math.bgu.ac.il/~ngur/Teaching/probability/
 one year ago

kropot72Best ResponseYou've already chosen the best response.1
\[P(14<X <26)=0.88490.1151=?\]
 one year ago

nickersiaBest ResponseYou've already chosen the best response.0
0.7698 which is 76.98% So, I suppose I got it right :) That's basically the same thing I did, thank you very much! :)
 one year ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.