Math Is Fun Forum

mantastrike

Member

Registered: 2011-04-24

Posts: 64

Please help me with my math homework!!

Students enrolled in an information technology course received the following marks in a computing subject in the first semester exam:

83, 77, 81, 38, 58, 92, 36, 39, 38, 79, 33, 24, 60, 84, 78, 69, 32

a) Construct a frequency distribution table with equal sized classes. If the first class will be "20 to less than 30"

b) Plot a histogram with equal class sizes
c) Plot the percentage distribution
d) Plot the cumulative distribution

THANK YOU!!

Bob

Administrator

Registered: 2010-06-20

Posts: 10,610

Re: Please help me with my math homework!!

Have a look at

http://www.mathsisfun.com/data/frequency-distribution-grouped.html

and

http://www.mathsisfun.com/data/histograms.html

Bob

Last edited by Bob (2011-05-11 19:48:11)

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mantastrike

Member

Registered: 2011-04-24

Posts: 64

Re: Please help me with my math homework!!

Marks               Frequency
24                           1
32                           1
33                           1
36                           1
38                           2
39                           1
58                           1
60                           1
69                           1
77                           1
78                           1
79                           1
81                           1
83                           1
84                           1
92                           1

can you please tell me if I got Question A correct?? what is the condition "If the first class will be 20 to less than 30?" I don't understand??

mantastrike

Member

Registered: 2011-04-24

Posts: 64

Re: Please help me with my math homework!!

Is my histrogram correct??
what equal class size??

PLEASE HELP ME!!

mantastrike

Member

Registered: 2011-04-24

Posts: 64

Re: Please help me with my math homework!!

I don't know how to do the percentage distribution and cumulative distribution

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Please help me with my math homework!!

Hi mantastrike;

I would start by putting the data into classes. They want the first class to be 20 - 29, so the next class will be 30 - 39 ( equal sizes ) and so forth. Now make a frequency table from your data.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

mantastrike

Member

Registered: 2011-04-24

Posts: 64

Re: Please help me with my math homework!!

I don't understand.

Please help me!!
I'll try to do another all nighter tonight, Please be online tomorrow so you can check all my work. I just need sleep.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Please help me with my math homework!!

All nighters are not the best way to go. If you do not show me what you are working on all night then I can not assist.

Did you read those pages that Bob sent you to?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,610

Re: Please help me with my math homework!!

hi mantastrike,

In post #4 your class sizes are not equal; in fact, worse than that, they aren't classes at all.  What you have is a bar chart.

To put the data into equal classes you have to do something like this:

class 20 ≤ x < 30     frequency = 1

class 30 ≤ x < 40     frequency = 6

and so on.

The classes are equal because 20 - 30 is a range of 10,             30 - 40 is a range of 10 and so on.

Then you make a regular scale on the x axis; the widths of the 'bars' will be 10.

The less than or equals at one end of the class makes it clear what to do with a mark exactly on the border of two classes.

The bars will run from 19.5 to 29.5; 29.5 to 39.5 etc.  This will cover the requirement of 20 but less than 30.

Notice I have made use of the continuous scale and allowed that each mark may have been rounded.

Post back what you have after that.

Bob

Last edited by Bob (2011-05-13 20:29:19)

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mantastrike

Member

Registered: 2011-04-24

Posts: 64

Re: Please help me with my math homework!!

I finished a b and c
My problem now is letter D

which is plot the cumulative distribution.

How can I get this??

Bob

Administrator

Registered: 2010-06-20

Posts: 10,610

Re: Please help me with my math homework!!

Please post your answers to a b and c.  The table, in particular is needed to help you with d.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mantastrike

Member

Registered: 2011-04-24

Posts: 64

Re: Please help me with my math homework!!

a) frequency is
1
6
0
1
2
3
3
1

                    __
6|                [  ]
5|                [  ]
4|                [  ]
3|                [  ]
2|                [  ]           _____
1|       _____[  ]     ___[        ]  ___
  |___ [____]__]__[___]____ ][___]
0  10  20  30  40  50  60 70 80 90

and my 20<30 % 5.88%
so on... 35.30%
0
5.88%
11.76%
17.65%
17.65%
5.88%

how do I get cumulative out of this?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,610

Re: Please help me with my math homework!!

hi mantastrike

The cumulative frequency values are what you get by adding up all the frequencies so far.

It will make more sense if you look at the table below.

The total below 30 is 1, the total below 40 is 1 + 6 = 7 ... and so on.

As there are 17 numbers you should find the last value you calculate is 17

Cumulative frequency graphs are line graphs.  You plot the point(s) at the end of each range thus:

(30,1)  (40,7) and so on up to (100,17).

Then join them with a smooth curve through the points.

Bob

Last edited by Bob (2011-05-14 01:11:45)

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mantastrike

Member

Registered: 2011-04-24

Posts: 64

Re: Please help me with my math homework!!

so is my cumulative
is

1
7
7
8
10
13
16
17

Right??

Bob

Administrator

Registered: 2010-06-20

Posts: 10,610

Re: Please help me with my math homework!!

Yes, that's right.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

MarshellaSmith

Guest

Re: Please help me with my math homework!!

You can submit your question on  the site offers 1 free math problem done in every 24 hours; for each student. They can comeback everyday.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Please help me with my math homework!!

They can comeback everyday.

How generous! They can come here 157 times a day.

I am not a big fan of that site or any site that forces people to pay for answers. Why should the OP go there? His question was answered well and for nothing! No limit on questions asked either.

Pay sites do not care what questions are asked. That includes contest problems, homework and yes exam questions. That kind of amoral activity is to be discouraged.

What about the people who cannot pay? So only the wealthy can cheat? What is wrong with this site may I ask?

Also I do not like spamming. Do you suppose you could paint your advertisements on the side of my car? Are you planning on cutting in MIF on the profits you make advertising here! He pays for bandwidth and it is unethical to use his to advertise yours without compensation.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.