Statistics and Probability Answers

A bag contains three red, four white and five black balls.

a) If three balls are taken without replacement, what is the probability that:

(i) they are all the same colour (ii) there are no black balls

(iii) there are 2 black balls (iv) there is one ball of each colour

there are 11 guys n 9 gals in a math club.two members of the club are chosen to represent the club for competition. Find the probability that the two members chosen are of the same sex

37. The Heldrich Center for Workforce Development found that 40% of Internet users received
more than 10 e-mail messages per day. A similar study on the use of e-mail was repeated in
2002.
A. Formulate the hypotheses that can be used to determine whether the proportion of Internet
users receiving more than 10 e-mail messages per day increased.
B. If a sample of 425 Internet users found 189 receiving more than 10 e-mail messages per day,
compute the test statistic
C. Compute the p value for the test statistic
D. At a = 0.5, what is your conclusion about the hypotheses?
E. state the conclusion within the context of the problem.

38. Five years ago the average size of farms in a state was 160 acres. from a recent survey of 27 farms, the mean and standard deviation were found to be 180 and 36 acres, respectively. Is there strong evidence that the average farm size is larger than what is was 5 years ago?

Five cards are lettered A,B,C,D,E. Three cards are picked at random, one after the other without replacement and are placed on a table. What is the probability that the cards will spell the word BED?

TK 1153 Statistics Assignment 1 (10%)
1. 2. 3.

Name

Matric No.

Instructions: I. Due on 27 Mar 2013 (Wed) at 12:30pm. 5 % will be deducted if I receive it less than 24 hours after due time. If I receive it 24 hours after due time, 10% will be deducted i.e. you’ll be getting 0% from this assignment.) II. Whenever SPSS package is used, you also have to write down all steps that lead you to conclusion and you have to submit data sheet and output to get full mark. III. Staple your assignment at the top left hand corner. Do not bind. Use A4 size paper only. IV. This assignment is to be done in a group of 3. Questions: 1. Atomic absorption spectrometry (AAS) analysis of sewage water samples for 10 months (January to October) in 2000 gave the following concentrations of zinc (μg/L). Jan Feb Mac Apr May Jun Jul Aug Sep Oct 195 182 204 202 190 186 192 198 193 188 a) Calculate the mean, variance and standard deviation of zinc concentration, and the 95% confidence interval of the mean zinc concentration for the year 2000. b) Assuming that the maximum allowable Zn content in sewage water is 185 μg/L. Is there evidence that the Zn concentration exceeded the maximum allowable value? In 1999, the concentrations of Zn in sewage water samples for the first 10 months of the year were as follows: Jan 193 Feb 180 Mac 200 Apr 198 May 185 Jun 183 Jul 190 Aug 194 Sep 188 Oct 187

d) Comparing the mean Zn concentration in 2000 with that of 1999, has the Zn concentration in sewage water increased? e) Is there any significant difference in the mean Zn concentrations in 2000 compared with that of 1999? 2. Titanium contents of steel (%) was determined by means of atomic absorption spectrometry by two students, John and Sulaiman. By using SPSS, answer the questions below: John 0.470 Sulaiman 0.448 0.529 0.463 0.490 0.449 0.489 0.482 0.521 0.454 0.486 0.477 0.502 0.409

a) Is there any significant difference in the precision of the two students? b) Is there any significant... [continues]

a hundred squash balls are tested by dropping from a height of 100 inches . a ball is fastt if it rises above 32 inches the average height of bounce was 30 inches and Standard deviation was 3/4.what is the chance of getting a fast standard ball

What is the difference between the null and alternative hypotheses statements in one-tailed and two-tailed tests? What are significance/alpha levels and how does using a one versus a two-tailed test affect significance levels?

Two eight-sided number cubes are thrown. Given that one of the cubes shows a three, what is the probability that the sum of the numbers that come up on the two cubes is nine?

a box containing 20 spark , of which 6 are defective , if tow plugs are selected from the box without replacement , what is the probability that both will be defective?

A spinner has the numbers 1 to 12 marked equally on the face. If the spinner is spun 2 times, determine the probability of it landing on a 7 and then an even number. State whether the events are dependent or independent.