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

step-by-step explanation:

i could only see the first page. the other pages were blurry. ; -;

x hot dogs for 2$, y drinks for 3$. 29 items and total 70

2x+3y=70

x+y=29

if x=17and y=12

2(17)+3(12)=70

34+36=70