1.The length (in millimetres) of a batch of 9 screws was selected at random from a large consignment and found to have the following information.

8.028.008.018.017.998.007.998.038.01

Construct a 95% confidence interval to estimate the true average length of the screws for the whole consignment.

From a second large consignment, another 16 screws are selected at random and their mean and standard deviation found to be 7.992 mm and 0.01mm. Can you conclude at 5% level of significance that the first batch of screws has greater mean than the second batch?

2.A sample of 8 independent observations provides the following:

3.63.93.84.54.94.24.43.8

Can you conclude at 5% level of significance that the mean is below 5?

3.A house cleaning service claims that they can clean a four bedroom house in less than 2 hours. A sample of n = 16 houses is taken and the sample mean is found to be 1.97 hours and the sample standard deviation is found to be 0.1 hours. (i)Construct a 95% confidence interval for the population mean of cleaning times. (ii)Conduct a hypothesis testing by using 0.05 level of significant to verify the claim.
4.A maker of toothpaste is interested in testing whether the proportion of adults (over age 18) who use their toothpaste and have no cavities within a six-month period is any different than the proportion of children (18 and under) who use the toothpaste and have no cavities within a six-month period. To test this, they have selected a sample of adults and a sample of children randomly from the population of those customers who use their tooth paste. The following results were observed.

AdultsChildren
Sample Size 100 200
Number with 0 cavities 83 165

Based on these sample data and using a significance level of 0.05, what...

...Normal(88.532,5.07943)
Normal(97.1033,5.04488)
Normal(107.15,5.15367)
Summary Statistics
Mean
88.532
Std Dev
5.0794269
Std Err Mean
0.2271589
Upper 95% Mean
88.978306
Lower 95% Mean
88.085694
N
500
Sum
44266
Summary Statistics
Mean
97.103333
Std Dev
5.0448811
Std Err Mean
0.2912663
Upper 95% Mean
97.676525
Lower 95% Mean
96.530142
N
300
Sum
29131
Summary Statistics
Mean...

...effectively. Mental Mathematics is the ability to utilise mathematical skills to solve problems mentally. The marks scored by pupils generate statistics which are used by teachers to analyse a student’s performance and development of theories to explain the differences in performance.
The Standard 3 class is where the transition from junior to senior level occurs where teachers expect the transference of concrete to abstract thinking would have occurred.
A...

...1. Introduction
This report is about the case study of PAR, INC. From the following book: Statistics for Business an Economics, 8th edition by D.R. Anderson, D.J. Sweeney and Th.A. Williams, publisher: Dave Shaut. The case is described at page 416, chapter 10.
2. Problem statement
Par, Inc. has produced a new type of golf ball. The company wants to know if this new type of golf ball is comparable to the old ones. Therefore they did a test, which consists out of 40...

...grams. D) 95% of reduced fat cookies have between 3.4 and 5 grams of fat. E) 95% of the cookies in the sample had between 3.4 and 5 grams of fat. Determine the margin of error in estimating the population parameter. 12) How tall is your average statistics classmate? To determine this, you measure the height of a random sample of 15 of your 100 fellow students, finding a 95% confidence interval for the mean height of 67.25 to 69.75 inches. A) 1.5 inches B) 0.25 inches C) 1.06...

...Confidence Levels:
a. 80%
Confidence level = 80%
or Significancelevel α= 0.2 / =(1-0.80)
No of tails = 2
Z value corresponding to 0.2 significancelevel and 2 tails = 1.2816
=NORMSINV(1-0.2/2)
=ROUND(NORMSINV(1-0.2/2),4)
b. 85%
Confidence level = 85%
or Significancelevel α= 0.15/ =(1-0.85)
No of tails = 2
Z value corresponding to 0.15...

...Statistics 1
Business Statistics
LaSaundra H. – Lancaster
BUS 308 Statistics for Managers
Instructor Nicole Rodieck
3/2/2014
Statistics 2
When we hear about business statistics, when think about the decisions that a manager makes to help make his/her business successful. But do we really know what it takes to run a business on a statistical level? While some may think that...

...of determining the answer. However, if you do so please do not simply provide “the answer”. For example, if you use Excel, be sure all appropriate formula calculations are visible. Note that all graphs, tables and other work must be labeled to a level of professional quality. All work is to be done independently. This quiz contains 7 questions in 4 pages.
1. (13 Points) The time in days between breakdowns of two machines is exponentially distributed with a mean time...

...1. A radio station that plays classical music has a “By Request” program each Saturday night. The percentage of requests for composers on a particular night are listed below:
Composers Percentage of Requests
Bach 5
Beethoven 26
Brahms 9
Dvorak 2
Mendelssohn 3
Mozart 21
Schubert 12
Schumann 7
Tchaikovsky 14
Wagner 1
a. Does the data listed above comprise a valid probability distribution?...