1. The life of a sample of 20 computer disks in number of days were recorded. The following table shows this data:

(Life of computer disks in number of days)

1025 897 795 1205 760
875 1000 1111 987 795
899 975 825 1099 1050
859 1075 1175 1125 1011

Perform the following tasks for the data given above:

Enter the data in a spreadsheet and create a frequency distribution in the ranges less than 750; 751 851 951 -1050; 1051 -1150; 1151 -1250; and more than 1250. Use array formula for finding the frequency distribution.

Draw the histogram of the data.

Find the relative frequency of the frequency distribution obtained In part

Find the mean and standard deviation of the data using spreadsheet formula.

2. A group of 8 typists were given a crash course in typing. The following table shows their typing speed before and after the course

Typing Speed in characters typed per minute

Before the Course 40 21 81 62 18 60 31 35

After the Course 42 29 79 62 25 61 34 36

Using t-test with a significance level of can you say that the crash typing course has helped in developing significant increase in typing speed? Clearly write Ho and H1 and explain your result. Make suitable assumptions, if any.