Question

X	19	20	21	22	23
P(x)	0.21	0.25	0.31	0.13	0.1

Find the mean, variance, and standard deviation of the distribution rounded to 4 decimal places.

Mean =

Variance =

Standard Deviation =

Approximately how many arrangements should the florist expect to deliver each week, rounded to the nearest whole number?

Answer 1

Solution

x	P(x)	x * P(x)	x2 * P(x)
0.25	0.21	0.0525	0.013125
20	0.25	5	100
21	0.31	6.51	136.71
22	0.13	2.86	62.92
23	0.1	2.3	52.9
	1	16.7225	352.5431

a ) Mean = = X * P(X) = 16.7225

b ) Variance = ² =X ² * P(X) - ²  

  =352.5443 - 279.6420

   =72.9021

Variance = 72.9021

c ) Standard deviation = =X ² * P(X) - ²  

=352.5443 - 279.6420

=72.9021

= 8.5382

Standard deviation = 8.5382