Question

Please answer all the questions below

2.1 Of the cars on a used car lot, 65% have air conditioning (AC), 45% have a CD player (CD) and 25% of the cars have both. What is the probability that a car has a CD player given that it has AC?

2.2 The table below reports the electricity expenses for a sample of 47 houses in Oshakati during January of 2017.

Electricity cost (in$)	Number of houses (fi)
20 - < 40	16
40 - < 60	9
60 - < 80	12
80 - < 100	10

2.2.1 Calculate the mean cost of electricity

2.2.2 Calculate the variance.

2.2.3 Calculate the mode

Please answer all the questions above

Answer 1

(2.2.1)

From the given data, the following Table is calculated:

Class	Mid value (x)	Frequency (f)	f.x	f.x2
20-40	30	16	480	14400
40-60	50	9	450	22500
60-80	70	12	840	58800
80-100	90	10	900	81000
Total =		n = 47

So,

Mean = 56.8085

(2.2.2)

So,

Variance = 543.9408

(2.2.3)

Maximum Frequency = 16

The mode class is 20 - 40

L = Lower boundary point of mode class = 20

f1 = Frequency of mode class = 16

f0 = Frequency of preceding class = 0

f2 = Frequency of succeeding class = 9

c = class width = 20

So,

Mode =33.9130