rest reciepts?

Question

the manager of a restaurant looks at the reciepts for the past two days the following table shows the range of values
amount of reciepts frequency of reciepts
0 - 0.99 ~ 17
1- 1.99 ~ 85
2- 2.99 ~ 140
3- 3.99 ~ 75
4- 4.99 ~ 82
5- 5.99 ~ 73
6- 6.99 ~ 62
7- 7.99 ~ 21
8- 8.99~ 14
9- 9.99 ~ 22
10 - 15 ~ 43
find a) D2 b)P87 and c) standard deviation

Answer 1

N = 634, 20%(634) = 126.8
2 < D2 < 2.99
87%(634) = 551.58
7 < P87 < 7.99
σ = 8.3341
m = $4.64