Please HELP with this question, I'm desperate!?

Question

Justin received a mark of 82%.
The mean is 71.325
The standard deviation is 9.2636248
Justin’s z-score is 1.15 (87.49) and he is in the 87th percentile
There are 40 people in his class.

Using the z-score table, what percent of the class should have a lower average mark than Justin? Is this true? Why or why not?

Link to z-score tables:

http://64.233.167.104/search?q=cache:ZKNRU6d1sFIJ:www.epatric.com/documentation/statistics/z-score_table.html+z-score+table&hl=en&ct=clnk&cd=1&gl=ca

http://www.epatric.com/documentation/statistics/z-score_table.html

http://64.233.167.104/search?q=cache:f_w4fD9Qc4EJ:www.admin.northpark.edu/jmcconnell/NPU%2520web/Web%2520Resources/z-score%2520Table.htm+z-score+table&hl=en&ct=clnk&cd=6&gl=ca

Below, you will find the marks for Justin’s class:

75
53
78
76
72
48
67
78
76
81
63
55
63
77
90
74
64
64
87
71
66
79
77
73
70
71
75
69
82
75
70
85
76
78
59
63
72
72
75
54

Answer 1

The percentage that should be below Justin is the 87.49 you referred to. (The z-score tables give it as a proportion, 0.8749.) By inspecting the data, we find that 90% had a score lower than Justin, which is pretty good agreement given that the sample size is 40 people and that each person therefore represents 2.5% of the class.