You are Here: Home >< Maths

1. hi!
I haven t done these in a while & don t have the answers to these questions,they re biology qs, I have to draw a histogram,can t remember how to get the frequency & how to organise this

Thanks
Attached Images

It can t be that impossible
3. Frequency density = Frequency divided by class width. After you've found the freq. dens. for each class interval. Label y 'frequency density' then draw the bars. Suppose 11-19 is a class interval, and 16 is the frequency. The bar would go up 2 (16 divided by (19-11)). and it would be very wide (from 11- 19 on the x axis)
4. (Original post by BrainFactory)
Frequency density = Frequency divided by class width. After you've found the freq. dens. for each class interval. Label y 'frequency density' then draw the bars. Suppose 11-19 is a class interval, and 16 is the frequency. The bar would go up 8 (16 divided by (19-11)). and it would be very wide (from 11- 19 on the x axis)
This is gonna sound really stupid but how do I get the frequency from the table
5. (Original post by hissyfit)
This is gonna sound really stupid but how do I get the frequency from the table
The figures that are not bold show the frequencies.
6. (Original post by BrainFactory)
The figures that are not bold show the frequencies.
So for the 1st one I do 30/(79-70)
or do I divide it by (139-120)
Sorry I m really clueless.
7. Attache the graph for you. Add in labels and I think that's correct
Attached Files
8. Histogram.docx (17.6 KB, 97 views)
9. (Original post by BrainFactory)
The figures that are not bold show the frequencies.

Method thanks to aliakhtar
You'd need to find out frequency density for each one which is basically Frequency/Class width

The class width of the first one is 120-139 so the width is 19.

The frequencies for the class 120-139 are : 13,14,17 ( Non-bold)

So the frequency density for those would be 13/19, 14/19 and 17/19. You'd plot the classes on the x-axis and the frequency density on the y-axis. Under the class 120-139 you would draw three bars in three different colors showing the the three different pressures. You'd make a key for the diastolic pressure each color shows. Make sure the bars are stacked together with no spaces in between.
10. (Original post by hissyfit)

Method thanks to aliakhtar
You'd need to find out frequency density for each one which is basically Frequency/Class width

The class width of the first one is 120-139 so the width is 19.

The frequencies for the class 120-139 are : 13,14,17 ( Non-bold)

So the frequency density for those would be 13/19, 14/19 and 17/19. You'd plot the classes on the x-axis and the frequency density on the y-axis. Under the class 120-139 you would draw three bars in three different colors showing the the three different pressures. You'd make a key for the diastolic pressure each color shows. Make sure the bars are stacked together with no spaces in between.

Correction : There would be no frequency densities as the last class has no width ( > or something . That's why in my graph I just plotted normal frequencies. Other than that I think my method is correct.
11. (Original post by hissyfit)

Method thanks to aliakhtar
You'd need to find out frequency density for each one which is basically Frequency/Class width

The class width of the first one is 120-139 so the width is 19.

The frequencies for the class 120-139 are : 13,14,17 ( Non-bold)

So the frequency density for those would be 13/19, 14/19 and 17/19. You'd plot the classes on the x-axis and the frequency density on the y-axis. Under the class 120-139 you would draw three bars in three different colors showing the the three different pressures. You'd make a key for the diastolic pressure each color shows. Make sure the bars are stacked together with no spaces in between.
It is fine. You can't do the last one because, like he said, it is >160 and has no width.
12. (Original post by BrainFactory)
It is fine. You can't do the last one because, like he said, it is >160 and has no width.
thanks a million
Rep for both of you in a couple of hours.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: December 5, 2010
Today on TSR

Find out how.

Want £10K to start a business?

Discussions on TSR

• Latest
• See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

How to use LaTex

Writing equations the easy way

Study habits of A* students

Top tips from students who have already aced their exams

Chat with other maths applicants

Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.