Question

Suppose that the average waiting time for a patient at a physician's office is just over 29 minutes. In order to address the issue of long patient wait times, some physicians' offices are using wait-tracking systems to notify patients of expected wait times. Patients can adjust their arrival times based on this information and spend less time in waiting rooms. The following data show wait times (minutes) for a sample of patients at offices that do not have a wait-tracking system and wait times for a sample of patients at offices with a wait-tracking system.

Without Wait- Tracking System	With Wait-Tracking System
25	33
65	9
16	15
22	18
35	10
46	32
12	9
27	3
12	12
32	17 Considering only offices with a wait-tracking system, what is the z-score for the 6th patient in the sample (wait time = 32 minutes)? If required, round your intermediate calculations and final answer to two decimal places. z-score = Suppose that the national average for the math portion of the College Board's SAT is 512. The College Board periodically rescales the test scores such that the standard deviation is approximately 75. Answer the following questions using a bell-shaped distribution and the empirical rule for the math test scores. If required, round your answers to two decimal places. (a) What percentage of students have an SAT math score greater than 587? % (b) What percentage of students have an SAT math score greater than 662? % (c) What percentage of students have an SAT math score between 437 and 512? % (d) What is the z-score for student with an SAT math score of 635? (e) What is the z-score for a student with an SAT math score of 425?

The owner of an automobile repair shop studied the waiting times for customers who arrive at the shop for an oil change. The following data with waiting times in minutes were collected over a one-month period.

9	11	3	12
11	4	3	3
4	24	13	22
5	18	6	9
12	23	15	2

(a)	Develop a frequency distribution using classes of 0-4, 5-9, 10-14, 15-19, and 20-24.

Class Frequency   0-4   5-9   10-14   15-19   20-24     Total

(b)	Develop a relative frequency distribution using the classes in part (a). If required, round your answers to two decimal places.
	Class Relative Frequency   0-4   5-9   10-14   15-19   20-24     Total

(c)	Develop a cumulative frequency distribution using the classes in part (a).
	Class Cumulative Frequency   0-4   5-9   10-14   15-19   20-24

Develop a cumulative relative frequency distribution using the classes in part (a). If required, round your answers to two decimal places.
	Class Cumulative Relative Frequency   0-4   5-9   10-14   15-19   20-24

(e)	What proportion of customers needing an oil change who wait 9 minutes or less?

Answer 1

Answe -2:

a) Frequency Distribution:

Class	Observations	Frequency
0 – 4	4, 4, 3, 3, 3, 2,	6
5 – 9	9, 5, 6, 9,	4
10 – 14	11, 12, 11, 13, 12,	5
15 – 19	18, 15,	2
20 – 24	24, 23, 22,	3
Total		20

b) Relative Frequency Distribution

= (Frequency of particular class / total size) * 100

Class	Frequency	Relative Frequency (%)
0 – 4	6	30
5 – 9	4	20
10 – 14	5	25
15 – 19	2	10
20 – 24	3	15
Total	20	100

c) Cumulative Frequency Distribution:

= Cumulative frequency is the sum of frequency of particular class plus frequency of all previous classes.

Class	Frequency		Cumulative Frequency
0 – 4	6	Up to 4	6
5 – 9	4	Up to 9	10
10 – 14	5	Up to 14	15
15 – 19	2	Up to 19	17
20 – 24	3	Up to 24	20
Total	20

d) Relative Cumulative Frequency Distribution

= (Cumulative Frequency / Total Size) * 100

Class	Cumulative Frequency	Relative Cumulative Frequency (%)
Up to 4	6	30
Up to 9	10	50
Up to 14	15	75
Up to 19	17	85
Up to 24	20	100

e) from relative cumulative frequecy distribution number of cutomer who eait for 9 minute or less are 10 and their their proportion is 50%.