The daily sales of an airtime vendor over a period of one month are summarised as follows:

Statistics
sales
N	Valid	30
Missing	0
Mean	31.4000
Std. Deviation	1.71778E1
Minimum	9.00
Maximum	86.00
Percentiles	25	18.5000
50	28.0000
75	39.0000

10- Mean =31.40 Std. Dev. =17.178 N =30 8- 6- Frequency 4- 2- 0.00 20.00 40.00 60.00 80.00 100.00 sales