Statistics revision paper 3

STATISTICS - REVISION PAPER 3


Table 1 - distribution of results by students in an exam

Mark 0-20 21-35 36-49 50-65 66-84 85-100
Frequency 2 7 13 34 27 9

Table 2 – phone calls recorded in a company

Time (mins) 0-4 4-8 8-12 12-16 16-20
No. of calls 5 9 15 8 3

Table 3 - two different tests (x and y) are performed to find the impurity level of steel alloys using six
specimens

x 1.3 1.3 1.6 1.4 1.7 1.7
y 1.5 1.5 1.7 1.8 1.9 1.8


TASKS

1 Using the data in table 1 find the:
a) Mean
b) Variance
c) Standard deviation
2 Using the data in table 1 draw the cumulative frequency curve and find the:
a) Median
b) Lower quartile
c) Upper quartile
3 Using the data in table 2 construct a histogram and find the:
a) Mode
b) Median
4 Using the data in table 3 calculate the:
a) Product moment correlation coefficient
b) Rank correlation coefficient

ANSWERS (calculations given to 2 decimal places)

1a 60.66
b 346.77
c 18.62

2a 60
b 49
c 73

3a 9.85
b 9.6

4a 0.82
b 0.87