Question

The amount of milk sold each day by a grocery store varies according to the Normal distribution with mean 130 gallons and standard deviation 12 gallons. On a randomly selected day, the probability that the store sells at least 154 gallons is
A. .0228.
B. .1587.
C. .8413.
D. .9772.

Answer 1

C. .8413.

Answer 2

Now I know the formula is x-mu/w/e that other greek letter is :P.

so (154-130)/12

Answer 3

why C?

Answer 4

got after solving...

Answer 5

When I look at Table A @ 2, I actually get A?

Answer 6

@CliffSedge :)

Answer 7

@soty2013 , you are completely useless. Why do you give answers with no explanation?

Answer 8

HAHA.

Answer 9

@KonradZuse , you have a normal distribution, N(130,12)
µ=130
σ=12
You know the z-score formula.
\[\large z=\frac{x-µ}{σ}\]

Answer 10

yessir and I got 2.

Answer 11

Here, the question is what is P(X>154) which is equivalent to 1-P(X<154)

Answer 12

From the homework and lectures I noticed that if it's negative or positive it still stick to w/e # it seems. @ -2.0 the choice was A...

Answer 13

So what is P(Z<2)?

Answer 14

Not sure if that's the correct why to do that.

Answer 15

Stick with Z=2, but the P-value you find for Z=2 will be for P(Z<2), and you want P(Z>2), so subtract P(Z<2) from 1.

Answer 16

ic so it's 1 - 0.228?

Answer 17

guess not that doesn't work.

Answer 18

I think I'm confused on what P() is.

Answer 19

Rewatching the video now.

Answer 20

??

P(Z<2)=0.9772

Answer 21

benford's law right?

Answer 22

Maybe. I don't remember what that is.

Answer 23

oh I forgot a 0.

Answer 24

I'm just using properties of continuous distributions and rules for probabilities.

Answer 25

okay so I was doing this right.

Answer 26

so yeah the answer is D then.

Answer 27

I kept getting confused with this because in the example of the law they show what each thing is.

Answer 28

No, the answer is definitely not (D)

Answer 29

Does it make sense that they have a nearly 98% chance of selling 24 gallons more than average?

Answer 30

no it doesn't lol.

Answer 31

Never forget the reality check!

Answer 32

By looking at this chart it shows 2 = 0.0228

Answer 33

I thought you wanted 1 - 0.0228

Answer 34

but now I see it's 1 - 0.9772.

Answer 35

which is what I was saying at the start... A?

Answer 36

No, P(Z<2)=0.9772 = 1- P(Z<-2).