Question

Please help :) Will give medal and fan :D


Use technology or a z-distribution table to find the indicated area.

The lengths of green beans for sale at a supermarket are normally distributed with a mean of 11.2 cm and a standard deviation of 2.1 cm. Consider a bag of 150 green beans.

How many green beans will be 13 cm or shorter?

Answer 1

he Rong he bad anser is 4

Answer 2

?

Answer 3

Find the z score first, from (score - mean)/SD: \[\large z = \frac{ x - \mu }{ \sigma }\]
Then use a z table to find the probability.

Then you can multiply by 150 beans.

Answer 4

I multiplied 0.8051*150 and I got 120.765

Answer 5

I got 121

Answer 6

is that correct? :)

Answer 7

Could you help me with this one too :)

Use the probability distribution graph to answer the question.

P(X≤a)=0.75P(X≤a)=0.75

What is the value of a?

Answer 8

*P(X≤a)=0.75

Answer 9

@agent0smith

Answer 10

i think a=1? :)

Answer 11

That one is really easy. The area of the rectangle for P(X≤a) must be 0.75. You have the height... it's 0.25. So work out what a is.

Answer 12

alright thankyou!!!!

Answer 13

a=1 is not correct btw.

Answer 14

ah ok i will make sure i fix that thanks :)

Answer 15

It's easy, work out what a is... the rectangle area must be 0.75, and the height is 0.25, so what x value gives an area of 0.75?

Answer 16

5?

Answer 17

Nope... look at the graph. Tell me the area between x=1 and x=2.

Answer 18

would it be 0.25 sorry if im not getting this right I've just started learning this :(

Answer 19

Yes. But this is basic geometry, don't make excuses :P

If the area between x=1 and 2 is 0.75, what about the area between
x=1 and x=3?
x=1 and x=4
x=1 and x=5?

Answer 20

1.5
2
2.25
3
is it wrong that i multiplied 0.75 by the spaces between the number?

Answer 21

Why would you multiply 0.75 by anything?

x=1 and x=3? - what is the base of the rectangle? what is the height?

Answer 22

If one 'column' is 0.25 (x=1 to x=2), then what is the area of two 'columns' (x=1 to x=3)?

Answer 23

0.5?

Answer 24

You should know for sure. This is easy. It's area of rectangles!

Answer 25

A=w*l know the length is 0.25 but like i said i dont know what to put in for the width

Answer 26

what i did before is that i counted the columns and the i multiplied it by 0.25 thats how i the got 0.5 :(

Answer 27

You can work out the width... with subtraction :P

what is the width if you're looking between x=1 and x=2? It's 1. What's the width between x=1 and x=3?

Answer 28

2

Answer 29

Yes. Now use that method to find the value of a:
P(X≤a)=0.75

Answer 30

the width between 1 and 5 is 4 and i multiplied that with the length 0.25 but i end up getting 1 :/ l*w=A 0.25*4=1

Answer 31

Ah ok i understand it now i saw what i did wrong

Answer 32

P(X≤a)=0.75
So then the value of a is...?

Answer 33

3 right you asked me what value gave me 0.75

Answer 34

Not quite. a is the x value. What x value gives an area of 0.75.

Answer 35

so 3 isn't the x value? because i used the formula and I multiplied 0.25 by 3 (the x value )which would then give me 0.75 :/

Answer 36

P(X≤a)=0.75
http://assets.openstudy.com/updates/attachments/57e0bbcee4b0860740296b37-narusamisty-1474349449600-capture.png
Look at the graph. Which x value gives an area 0.75?

Answer 37

oh its 4... ._.

Answer 38

Yes.

Answer 39

thankyou for helping me. :)

Answer 40

Welcome :)