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Simple Tips for Better Maths Results!
A parent recently sent me some questions and I would like to share with you this one on Cumulative Frequency.
The tricky part of question (c) is reading the scale correctly.
For (ii), total number of students (160) represent the entire pie chart which is 360 degrees.
Therefore, by proportion, we can find out the degrees of the pie chart for students who are awarded C grade.
Link to what was previously discussed in Statistics (an Elementary Math E-Math topic) in Drawing & Understanding of Cumulative Frequency, here are the 5 features for a Box & Whisker Plot (I guess you would know which part represents the box, and the portion which are the whiskers)
Note the difference between these 2 terms:
Range = Max - Min
Interquartile Range (IQR) = Q3 - Q1
Let's use this question to discuss on drawing and using cumulative frequency curve.
(Click on image to enlarge)
(a) Drawing of cumulative freq curve
(Click on image to enlarge)
Step by step solutions:
Notes:
140 pupils weigh 72.5 kg or less. So if you are interested to find out the number of pupils who weigh more than 72.5 kg. It will be 280 (total number of pupils) - 140 = 140 pupils.
Special attention to (iii) no. of students who weigh more than 65kg. By going UP & ACROSS, we get 20 students. This only means 20 students weigh 65 kg or less. So the rest (280 - 20 = 260) will weigh more than 65 kg
In my next post, I will be discussing the features of box and whisker plot.
Need graph paper but had none at home!
This was the situation I faced yesterday. I needed some graph papers urgently for plotting of some cumulative frequency graphs but they simply ran out when I check my drawers.
I am sure some of you had the same experience like me before.
This incident reminded me of another funny thing that happened back during my old school times.
We had this very fierce Math teacher whom everyone was very fearful of. We were learning something about graphs during that time and she was returning us our graph assignments. She made a "special mention" to a classmate of his remarkable! effort of creating his own graph paper! Really drawing out the squares manually!
:)
Lesson learnt : " Go Google and type in "Free Graph Papers". You will get an endless list of sites which provide all the different kinds of graph papers that you will need.
Cheers to technology!