The following table shows an estimated probability distribution for the sales of a new product in its first week:
|
Number of units sold
|
0
|
1
|
2
|
3
|
4
|
5
|
|
Probability
|
0.05
|
0.15
|
0.20
|
0.35
|
0.15
|
0.10
|
What is the probability that in the first week:
(a) Four or five units will be sold;
(b) At least 3 units will be sold;
(c) At least 1 unit will be sold?