Q3a) A manager of a computer store knows that 19% of PC sold out returned to his store forrepair within one year. Five of these PCs, whose characteristic can be assumed to beindependent of each other, are sold out.(i) What is the probability that at most two of these PCs have returned for repair?(ii) Find the mean number of PCs returned for repair and also find its variance.

Answer: Given that: p=0.19 , n= 5 now will use Binomial probability P(X=x)=nx*px*(1–p)n–x,where…

Answered: a) A manager of a computer store knows…

A First Course in Probability (10th Edition)

10th Edition

ISBN:9780134753119

Author:Sheldon Ross

Publisher:Sheldon Ross

Chapter1: Combinatorial Analysis

Section: Chapter Questions

Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...

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4 Thirty five percent of the students in a class of 100 are planning to go to graduate school, Find the variance of this binomial distribution
The aim of a study is to test the ratio of variances in the weight of two groups of rats being under a certain drugs A ( group 1) and B ( group 2) . A random sample of 16 rats was selected from group land 13 rats from group 2, Then their weight were recorded. The results are shown in the following table n Mean Median sd group 1 16 3.5 3.0 1.05 group 2 13 2.20 2.0 1.15 F15,12,0.05 = 0.404 F 19,16,0.025 = 0.386 F16,10,0.025 =0.335| F16,10,0.05 =0.401 F15,12,0.1 =0.496 F19,16,0.05 =0.451 F10,16,0.025 = 0.286 F 12,15,0.05 =0.382 F16,19,0.025 = 0.371| F10,16,0.05 = 0.354 F12,15,0.1 =0.475 F16,19,0.05 = 0.437| Construct a 95% confidence interval for the ratio of the variances. [ Hint: because of the rounding select the closest interval ] O a. None of these O b. [ 2.488, O0.238 ] O c. [ 2.160 , 0.309] O d. [2.063 , 0.318]
The burning life (in hours) of electric lamps installed in a street of a city follows a normal distribution with an average of 120 burning hours and variance of 54000 square minutes. Find the probability of the electric lamps that are likely to burn for more than 110 hours more than 5124 minutes and less than 7450 minutes
Two surfers and statistics students collected data on the number of days on which surfers surfed in the last month for 30 longboard (L) users and 30 shortboard (S) users. Treat these data as though they were from two independent random samples. Test the hypothesis that the mean days surfed for all longboarders is larger than the mean days surfed for all shortboarders (because longboards can go out in many different surfing conditions). Use a level of significance of 0.05. Longboard: 4,9,8,4,9,8,8,6,7,9,11,11,11,13,12,16,14,9,11,18,20,15,10,16,20,20,8,20,21,23 O Shortboard: 6,4,4,6,8,8,6,9,4,6,7,5,9,7,4,16,13,11,13,13,11,15,10,10,13,14,11,21,21,12 Determine the hypotheses for this test. Choose the correct answer below. O A. Ho: HL = Hs O B. Ho: HL = Hs OC. Ho: HL # Hs Ha: HL Hs O F. Ho: HL = Ps Ha: HL = Ps Ha: HL = Hs Ha: HL > Hs Find the test statistic for this test. t = (Round to two decimal places as needed.) Find the p-value for this test. p-value = (Round to three decimal places…
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Cigarette packets used to contain cards representing such things as flowers, film stars or football teams. A complete set would comprise n different cards, say, and collectors would aim to obtain a complete set. Clearly, the first packet bought would contain a new card which would start the collection. The next card obtained might simply duplicate the first card, or it might also be a new card, and add to the collection, and so on. Obtain expressions for the mean and variance of the number of packets which must be purchased until a complete set of cards is obtained.
Consider X is a random variable and has equal probability of being -1,0,+1. What is the correlation between X and Y while Y=X*X.
We are interested in determining whether or not the variances of the sales at two music stores (A and B) are equal. A sample of 16 days of sales at store A has a sample variance of 20 while a sample of 26 days of sales from store B has a sample variance of 30. The test statistic is (A) 1.50 (B) 1.69 (C) 2.25 (D) 2.50
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A dietician is researching two new weight gain supplements that have just hit the market: Ripped and Gainz. She wants to determine if there is any difference between the two supplements in the mean amount of weight gained (in kg) by the people who take them. The dietician tracks the total weight gain (in kg) over a year of a random sample of 14 people taking Ripped and a random sample of 12 people taking Gainz. (These samples are chosen independently.) These data are shown in the table. Total weight gains (in kg) Ripped Gainz 14.1, 10.9, 12.1, 5.2, 12.0, 17.1, 9.0, 14.8, 11.2, 6.8, 12.4, 8.5, 12.1, 10.5 Send data to calc... v 7.6, 9.5, 8.6, 10.8, 7.9, 10.0, 8.4, 6.2, 8.6, 10.2, 8.9, 8.2 Send data to Excel Assume that the two populations of weight gains are approximately normally distributed. Can the dietician conclude, at the 0.05 level of significance, that there is a difference between the population mean of the weights gained by people taking Ripped and the population mean of the…

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