From past results, a professor knows that the test score of a student taking her final examination is a random variable with mean 65 and a variance known to be 15. what is the probability that a student will score between 50 and 80? (7-8.1.2)

(a) somewhere between 0.75 and 0.85
(b) exactly 0.6826
(c) exactly 0.9333
(d) somewhere between 0.55 and 0.75

option B

Step-by-step explanation:

Given,

mean result (μ) = 65

standard deviation (σ)= 15

probability that student will score between 50 and 80

=

=

=

 = P(Z < 1) - P(Z < -1)

Using z table,  

= 0.8413 - 0.1587

= 0.6826

the correct answer is option B

median is the value separating the higher half of a data sample, a population or probablity distribution from the lower half.

step-by-step explanation:

say you have 3,8,7,3,1,9,8 order them from lowest to highest

if orderd it would be 1,3,3,7,8,8,9 now you take away from the lowest and the highest until you end up in the middle.

so you would remove the 1 and 9 leaving you with 5 digits remaining

when you've reached the middle that would be your answer so in this case the answer is 7

if there were two numbers left say 7 and 5 you'd and them together so 12 then divide by 2 witch would equal 6 so the answer would be 6

good luck on that project hoped i you at all