Exercise #2. The masses, m grams, of 690 medical samples are given in the following table.

Mass (m grams)4 ≤ m < 1212 ≤ m < 2424 ≤ m < 28
No. medical samples (f)224396p

a. Find the value of p that appears in the table.

p=690-(224+396)=70

b. On the graph paper, draw a histogram to represent the data.

c. Calculate an estimate of the number of samples with masses between 8 and 18 grams.

The estimate number of samples with masses between 8 and 18 grams is (224:2)+(396:2)=310

Exercise #3. The table below shows the heights, in metres, of 50 boys and of 50 girls.

Height (m)1.2 —1.3 —1.6 —1.8-1.9
No. boys (f)711266
No. girls (f)1022162

a. How many children are between 1.3 and 1.6 metres tall?

Each class:
1.2-1.3 = 17
1.3-1.6 = 33
1.6-1.8 = 42
1.8-1.9 = 8

Frequency density:
a — 17
b — 11
c — 21
d — 8

Between 1.3 and 1.6 m tall there are 33 children.

b. Draw a histogram to represent the heights of all the boys and girls together.

c. Estimate the number of children whose heights are 1.7 metres or more.

21+8=29 children