Question

I REALLY need math homework help!! please respond! Please!!!

Answer 1

?

Answer 2

Can you help me with this question? In a large population, very close to 25% of the observations will fall below the 25th percentile?
(Q1), and close to 75% fall below the 75th percentile (Q3). The Web Site of the Educational Testing Service reports that on the SAT Verbal test, with a possible perfect score of 800, the 96th percentile of 1,475,623 scores nationwide is a score of 720

What is the best estimate of exactly how many scores were below 720

Answer 3

sorry been years since stats class. something to do with a z score:)

Answer 4

Thanks for responding, but I really need help with stats.

Answer 5

In a large population, very close to 25% of the observations will fall below the 25th percentile?
(Q1), and close to 75% fall below the 75th percentile (Q3). The Web Site of the Educational Testing Service reports that on the SAT Verbal test, with a possible perfect score of 800, the 96th percentile of 1,475,623 scores nationwide is a score of 720

What is the best estimate of exactly how many scores were below 720

Answer 6

It states that "the 96th percentile ... is a score of 720", so this literally means that 96% of all the total scores were below 720


So just take 96% of the total (1,475,623) to get your estimate

Answer 7

Alright :) Thanks, do u have time to help with another question?

Answer 8

yw, sure go for it

Answer 9

Okay, just one sec....

Answer 10

ok

Answer 11

Make a modified boxplot for this distribution..
25,34,46,37,33,42,40,37,34,49,73,46,45,45,5

Answer 12

Here's a good page that explains how to construct a modified box plot (and they provide examples as well)

http://www2.selu.edu/Academics/Faculty/dgurney/Math241/StatTopics/BoxGen.htm

Let me know if this helps or not

Answer 13

ok, thanks :)

Answer 14

you're welcome

Answer 15

shoot, I'm still having trouble.

Answer 16

which part are you stuck on

Answer 17

well, my math homework is multiple choice and the boxplots they have are really similar.

Answer 18

hmm can you show me?

Answer 19

Doesn't allow me to copy my homework ..

Answer 20

well maybe the scales are different even though the pics look the same?

Answer 21

it's hard to say without looking at the pic

Answer 22

That is true

Answer 23

does any of the pics have a star (or two) in them?

Answer 24

or a dot?

Answer 25

no

Answer 26

could it be that the last value in that list isn't a 5, but a 50 or something?

Answer 27

I answered it the best I could and it was correct and on the next question, its the same type of question though,

Answer 28

so basically another problem having you construct a modified box plot?

Answer 29

btw, I found this solver

http://www.alcula.com/calculators/statistics/box-plot/

that will make box plots if you type in the data...I'm not sure if it does modified box plots though

Answer 30

Oh wait, never mind. sorry. They are asking me to find the first quartile

Answer 31

oh, find the median, then focus on the lower half and find the median to find the first quartile

Answer 32

in this distribution
24,26,26,27,28,31,33,35,37,38,40,42,43,46,48,55,56

Answer 33

I should state that you need to sort the data first and foremost.

Answer 34

so first step is to sort in ascending order (ie least to greatest)

Answer 35

it looks like that that is already done

Answer 36

now find the median

Answer 37

37

Answer 38

good

Answer 39

The median cuts the data set in half. So you have the lower half of

24,26,26,27,28,31,33,35

and the upper half of

38,40,42,43,46,48,55,56


-------------------------------------------------------

The first quartile Q1 is the median of the lower half

Answer 40

27?

Answer 41

not quite

Answer 42

27.5?

Answer 43

yes

Answer 44

ok :)...what is the interquartile range?

Answer 45

Interquartile range (IQR) is...

IQR = Q3 - Q1


So you need the third quartile

Answer 46

So you do the same thing, but now to the upper half.

Answer 47

Side note: the IQR is basically the width of the box in the box and whisker plot

Answer 48

alright

Answer 49

They gave me a new distribution and are asking what that Q3 is

Answer 50

ok, do the same thing as you did before, but focus on the upper half this time

Step 1) Find the median

Step 2) Cut the data set into two halves

**Different step** Step 3) Focus on the upper set and find the median to find Q3 **Different step**

Answer 51

okay so the numbers are
10,25,18,31,16,27,5,13,32,24,15,21,18,18,24,4,8,11,11,23

Answer 52

Oh I always forget, but remember to sort first

Answer 53

So start by sorting the data set

10,25,18,31,16,27,5,13,32,24,15,21,18,18,24,4,8,11,11,23

Answer 54

from least to greatest

Answer 55

4,5,8,10,11,13,15,16,18,23,25,31

Answer 56

one sec while I compare

Answer 57

ok

Answer 58

I see one copy of 11 in your list, but there are two "11" values

Answer 59

when I sorted, I got a much bigger list and I got

4,5,8,10,11,11,13,15,16,18,18,18,21,23,24,24,25,27,31,32

Answer 60

somehow, you got rid of the duplicate entries, but you actually want to keep them

Answer 61

Ohh, ok, soo the median is 18, right?

Answer 62

yes, the median is 18

Answer 63

and from 18 you cut it in half to get
18,21,23,24,24,25,27,31,32

Answer 64

that median is 24?

Answer 65

or is 24 the Q3 of the distribution?

Answer 66

you are correct

Answer 67

24 is the median of that upper half and it's the value of Q3

Answer 68

cool :)

Answer 69

Do you know anything about polynomials?

Answer 70

yes I do, what do you want to know about them?

Answer 71

well, how do I factor a number, variable or expression out the polynomial?

Answer 72

do you have a specific polynomial you want to work on?

Answer 73

5x(3x+1)+7(3x+1)

Answer 74

So what do you see in common here?

Answer 75

5x, 3x, 3x?

Answer 76

hmm let me restate it another way

we have 5x(3x+1)+7(3x+1), which can be broken up into


First term: 5x(3x+1)

Second term: 7(3x+1)


What is common among the two terms above?

Answer 77

(3x+1)

Answer 78

good, so you can factor it out of the entire expression

Answer 79

do you know how?

Answer 80

noo

Answer 81

Say we have 3x+5x, we can factor out the common term x to get x(3+5)


So if we let z = 3x+1, we go from

5x(3x+1)+7(3x+1)

to

5xz+7z


Then we can factor out this common term z to get


z(5x+7)


Finally, we replace z with 3x+1 to get


(3x+1)(5x+7)

Answer 82

okay, but it says to use ( 3x+1) and to factor out the number that each term as in common from the polynomial and multiply by the fully factored polynomial.

Answer 83

(3x+1) is that common factor and it's factored in the work shown above

Answer 84

why would it want to multiply by the fully factored polynomial?

Answer 85

hmm maybe they meant to multiply it out and check?

Answer 86

maybe...the next question seems more complicated. Its the same idea but with -3x^3 + 12x^2 + 36x

Answer 87

take it each term at a time

First term: -3x^3
Second term: 12x^2
Third term: 36x

What's the GCF here?

Answer 88

6

Answer 89

not quite

Answer 90

3?

Answer 91

getting better, but notice there are x terms in each term

Answer 92

so its 3x?

Answer 93

yes

Answer 94

what are the common terms?

Answer 95

3x is that common term, so factor it out and you can optionally factor out a negative to make that leading term positive to go from


-3x^3 + 12x^2 + 36x

to

-3x(x^2 - 4x - 12)

Answer 96

Now can you factor x^2 - 4x - 12 at all?

Answer 97

I don't know how..

Answer 98

Find two numbers that multiply to -12 AND add to -4