Can you explain this Statistics question to me ?
The following are the grade that 50 students obtained on an accounting test:
73 65 82 70 45 50 70 54 32 75
75 67 65 60 75 87 83 40 72 64
58 75 89 70 73 55 61 78 89 93
43 51 59 38 65 71 75 85 65 85
49 97 55 60 76 75 69 35 45 63
(a) Show a stem-and-leaf display of these values. Use the tens digit to form the stem.
(b) Group these grades into a distribution having the classes 30-39, 40-49, 50-59, ....., and 90-99
(c) Convert the distribution obtained in part (b) into a cumulative "less than" distribution, beginning with "less than 30."
2) The following are the miles per gallon obtained with 40 tankfuls of gas:
24.1 25.0 24.8 24.3 24.2 25.3 24.2 23.6 24.5 24.4
24.5 23.2 24.0 23.8 23.8 25.3 24.5 24.6 24.0 25.2
25.2 24.4 24.7 24.1 24.6 24.9 24.1 25.8 24.2 24.2
24.8 24.1 25.6 24.5 25.1 24.6 24.3 25.2 24.7 23.3
(a) Group these figures into a distribution having the classes 23.0-23.4, 23.5-23.9, 24.0-24.4, 24.5-24.9, 25.0-25.4 and 25.5- 25.9.
(b) Convert the distribution obtained in part (a) into a cumulative "or more" distribution, beginning with "23.0 or more" and ending with " 26.0 or more.