Question

Can someone help with probability?

Answer 1

@TheSmartOne

Answer 2

can you help @xapproachesinfinity

Answer 3

i don't remember the prob equation for standard deviation and mean
i believe this is just a direct use of that equation

Answer 4

oh...

Answer 5

hm how about reading what that graph is saying

Answer 6

taller than 66.7 would be 13.5+2.35=15.85%

Answer 7

my guess

Answer 8

I dunno....

Answer 9

well i don't remember any of this stuff
just think that's what the graph is showing hehehe
don't believe me though haha

Answer 10

15.85% is correct

Answer 11

can you explain @Zarkon ?

Answer 12

you are just adding the percentages that lie above 66.7in

Answer 13

the probability is the area under the curve from 66.7 to infinity

Answer 14

why do you add those 2 numbers though?

Answer 15

those are the ones above 66.7

Answer 16

is this the integral \[\int e^{-x^2}dx\]

Answer 17

how do you do part b?

Answer 18

add up the probabilities and then multiply by 300

Answer 19

Let \(X\sim N(\mu,\sigma^2)\)

then \[P(X\le x)=\int\limits_{-\infty}^{x}\frac{1}{\sqrt{2\pi\sigma^2}}e^{\frac{-(t-\mu)^2}{2\sigma^2}}dt\]

Answer 20

woah, I'm sorry, but that's Greek to me XD

Answer 21

though you don't need to use that here since the probabilities are already given

Answer 22

i completely forgot this thing!
so mu is the mean?

Answer 23

yes

Answer 24

i see, thanks :)

Answer 25

what do you mean the prob. are given?

Answer 26

so in generality in \[\int e^{-x^2}dx\] where x is the random variable
i remember this integral from calc one of those special integrals

Answer 27

the probabilities are given to u
the percentages are the chances

Answer 28

just add them up and multiply by 300

Answer 29

wait, so 13.5+34+34+13.5

Answer 30

yes

Answer 31

=94.9

Answer 32

multiply by 300

Answer 33

94.9*300=28470

Answer 34

sounds good :)

Answer 35

that doesn't make sense, pertaining to the question...

Answer 36

why is not reasonable?

Answer 37

if the data's based on 300 students, how is the number greater than 300?

Answer 38

oh you should divide the percentages by 100

Answer 39

add those values and divide by 100 before you multiply

Answer 40

so divide 94.95 by 100? why?

Answer 41

we are looking for prob not percentages

Answer 42

oh, okay

Answer 43

should make since now :)

Answer 44

284.85... and since we're talking about people, I would need to round. would I round up?

Answer 45

yeah

Answer 46

oh, okay, thanks!

Answer 47

np!