Question

B. Determine whether or not the table is a valid probability distribution of a discrete random variable. Explain fully.

X	0.23	0.14	0.17
P(X=x)	-0.22	0.38	0.84

1. Daily sales of a medium sized restaurant are normally distributed with a mean of $720 and a standard deviation of $80.
2. What is the probability that a randomly selected day will make a sales of at least $656?
3. What is the probability that a randomly selected day will make a sales between $680 and $840?
4. What is the lowest amount of sales to put a day above the top 10% of daily sales?

Donor ID	Number of days before the next donation
1	33
2	37
3	34
4	36
5	33
6	32
7	34
8	33
9	32
10	35
11	32
12	36
13	32
14	34
15	35
16	35
17	35
18	33
19	32
20	33
21	35
22	31
23	35
24	34
25	35
26	36
27	37
28	36
29	33
30	33
31	34
32	35
33	31
34	34
35	34
36	36
37	33
38	33
39	34
40	37
41	32
42	31
43	35
44	31
45	37
46	36
47	37
48	31
49	31
50	36
51	35
52	36
53	32
54	33
55	33
56	33
57	33
58	35
59	35
60	36
61	32
62	34
63	36

Answer 1