A typing test is taken by 111 people. The numbers of typing errors they make in the test are summarized in the table below. (Marks 5) Number of typing errors
1-5
6-10
11-15
16-20
21-25
Frequency
24
9
21
15
42
Draw a histogram to represent this information.
Calculate mean number of typing error for these 111 people.
State which class contains the lower quartile and which class contains the upper quartile. Hence find the least possible value of the inter-quartile range.
Find standard deviation of these 111 people.