Quartile and Percentiles. Need urgent help.
-
The noise level in a secondary school premise was tested and 400 readings at different times and locations were recorded. A report on the test provided the following infomation.
18 reading were less than or equal to 50 dB
no readings > 75 dB
the median noise level = 62 dB
lower quartile of distribution = 54 dB
interquartile of distribution = 12 dB
the upper quartile should be 66 dB
now the question wants me to draw a cumulative frequency curve of the distribution.
i obtained the following coordinates(54,100), (62, 200), (66,300). However, I would need 2 more coordinates to be able to draw the graph. May I know how I can use the data that says:
18 reading were less than or equal to 50 dB
no readings > 75 dB
thank you.
-
Originally posted by anpanman:
18 reading were less than or equal to 50 dB
no readings > 75 dB
18 reading were less than or equal to 50 dB. Guess that means you should have another coordinate at (50,18)And no readings > 75 dB means that the right tail of your cumulative frequency curve should end at (75,0)?
The starting coordinate should also be (0,0)?
-
i think ''no readings > 75 dB'' it means (75,400). This is also logic as culmulative frequency only goes up..
-
The first point is (0,0) and the second point is (18,50) lah, not (50,18) hor and the last point will be (75,400) lor.
-
Originally posted by Lee012lee:
The first point is (0,0) and the second point is (18,50) lah, not (50,18) hor and the last point will be (75,400) lor.
well done
