Question

Use the following information for the next three (3) questions: In the table below, X represents the number of long distance calls made by a store manager to suppliers during one hour. X 0 1 2 34 19, P(X 2) = (a) 0.2 (b) 0.3 (c) 0.4 (d) 0.7 20. Calculate the expected number of calls (μ) during one hour. (a) μ-10 (b) μ-2 (c) μ = 0.4 (d) μ=0.2

Answer 1

X	P(x)	XP(X)	$(X-\mu _x)^2$	$(X-\mu _x)^2P(x)$
0	0.2	0	4	0.8
1	0.1	0.1	1	0.1
2	0.4	0.8	0	0
3	0.1	0.3	1	0.1
4	0.2	0.8	4	0.8
	Mean	2	Variance	1.8

19) Sum of probability= 1

P(0)+P(1)+P(2)+P(3)+P(4)=1

0.2+0.1+P(2)+0.1+0.2=1 =>P(2)= 0.4

20) $\mu _x= \sum X_iP(x)= 2$

21) $\sigma ^2= \sum (X-\mu _x)^2P(x) =1.8$