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Practice

Statistics II

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4.

5. Answer the whole of this question on a sheet of graph paper.

6. Answer the whole of this question on a sheet of graph paper.

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8.

9. The cumulative frequency table shows the distribution of the ages, in years, of the

residents of a block of flats.

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(a) Find the value ofa, ofb, ofc and ofdin the table to represent the information.

Age (x years) Number of residents

0

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Homework

Statistics II

1. The cumulative frequency curve shows the heights of 120 boys.

(a) Find the value ofa, ofb and ofc in the table to represent the information.

Height (h cm) Cumulative frequency

h 140 0

h 145 ah 150 29

h 155 b

h 160 88

h 165 c

h 170 120

(b) Use the curve to estimate

(i) the median,

(ii) the lower quartile,

(iii) the upper quartile,(iv) the interquartile range.

(c) Estimate the number of boys whose height is greater than 168 cm.

(d) Find the percentage of the boys whose height is 152 cm or less.

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2. The percentage cumulative frequency curve shows the masses of 80 girls.

(a) Find the value ofa, ofb and ofc in the table to represent the information.

Mass (w kg) Number of girls

w 40 0

w 45 a

w 50 28

w 55 b

w 60 72

w 65 c

w 70 80

(b) Use the curve to estimate

(i) the median,

(ii) the interquartile range.

(c) If 80% of the girls are less than or equal tox kg, find the value ofx.

(d) Find the percentage of the girls whose mass is more than 48 kg.

3. The cumulative frequency curve shows in a survey, 94 motorists were asked to report the

distances they had travelled last weekend.

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(a) Find the value ofa, ofb and ofc in the table to represent the information.

Distance (x km) Number of motorists

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(c) Use the curve to find

(i) the median of the distribution,

(ii) the interquartile range,

(d) Find the percentage of the students living within 5 km from the school.

(e) Find the percentage of the students living beyond 9 km from the school.

(f) If 80% of the students live withiny km from the school, find the value ofy.

End of Homework

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