Edexcel Mathematics Higher Tier, November 2009 (1380/4H) (Paper 4, calculator)


Question 27


a) Frequency density =   


We can work this out for the 2nd category (30  t  40)


Frequency density =   = 3.5 now we can see what the scale is on the histogram. From this we can


Time (t minutes) 0 t30 30 t 40 40 t 60 60 t 80 80 t 120


Frequency 30 note 5 35


60 note 6 30 20


Class width 30 10 20 20 40


Frequency density 1 note 4


3.5 note 1 3 note 4


1.5 note 2 0.5 note 3


note 1: 35 ÷10 = 3.5 note 2: 30 ÷ 20 = 1.5 note 3: 20 ÷ 40 = 0.5 note 4: now we know the scale these are read off the y axis of the histogram


frequency = frequency density x class width note 5: 1 x 30 = 30 note 6: 3 x 20 = 60


b)


now read off the frequency density for the first and third category. For 0  t  30 frequency density is 1, for 40  t  60 frequency density is 3


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