A particular telephone number is used to receive both voice calls and fax messages. Suppose that 20% of the incoming calls involve fax messages, and consider a sample of 20 incoming calls. (a) What is the expected number of calls among the 20 that involve a fax message? (b) What is the standard deviation of the number among the 20 calls that involve a fax message? (Round your answer to three decimal places.) (c) What is the probability that the number of calls among the 20 that involve a fax transmission exceeds the expected number by more than 2 standard deviations? (Round your answer to three decimal places.)

A particular telephone number is used to receive both voice calls and fax messages. Suppose that 20% of the incoming calls involve fax messages, and consider a sample of 20 incoming calls. (a) What is the expected number of calls among the 20 that involve a fax message? (b) What is the standard deviation of the number among the 20 calls that involve a fax message? (Round your answer to three decimal places.) (c) What is the probability that the number of calls among the 20 that involve a fax transmission exceeds the expected number by more than 2 standard deviations? (Round your answer to three decimal places.)

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...

See similar textbooks

Similar questions

2.Suppose that 60% of middle school students in San Diego wear braces. A random sample of 250 San Diego middle school students is selected. a.What is the mean and standard deviation of the 250 samples students that will have braces? b.What is the probability that at most 190 students in the sample wear braces?
The ages of students in a middle school have the following probability distribution: x 12 13 14 15 P(x) 0.25 0.29 0.32 0.14 a) What is the probability a student chosen at random is no less than 13 years old? b) What is the mean age of the students in middle school? c) What is the standard deviation for the ages of the students in the middle school?
A department store manager has monitored the number of complaints received per week about poor service. The probabilities for numbers of complaints in a week, established by this review, are shown in the table. Number of complaints Probability 0 0.16 1 0.26 2 0.35 week? 3 0.10 4 0.08 5 0.05 What is the standard deviation of complaints received per Please round your answer to the nearest hundredth. Note that the correct answer will be evaluated based on the full-precision result you would obtain using Excel.
Records of a health insurance company show that 30% of its policyholders over 50 submit a claim during the year. 15 policyholders over 50 are selected at random; what is the probability that at least 10 will submit a claim during the year? What is the probability that 4 will submit a claim during the year? How many do you expect to submit a claim. What is the standard deviation?
Incomes in a certain town are strongly right-skewed with mean $40,000 and standard deviation $8,000. A random sample of 5 households is taken. What is the probability the average of the sample is more than $42,000?
If the probability that a certain measuring device shows an excessive deviation is 0.14. What is the probability that the 16th of these metering devices tested will be the sixth to show excessive deviation? Answer: What is the probability that at most 19 measuring devices must be tested to find the seventh that shows excessive deviation? Answer: What is the standard deviation of the number of measuring devices that must be tested to find the eleventh with excessive deviation? Answer: Note: Answer with at least 4 decimal places
Q)In a certain large university, students spend on average $75 a month on pizza, with a standard deviation of $24.30.A marketing specialist plans to survey 225 students, and ask them to record how much they spent on pizza during April.(a) What would be the standard deviation of the sample mean?(b) What is the probability that the researcher will get a sample mean less than $72.5?
Suppose the heights of 18 year old men are approximately normally distributed, with mean 71 inches and standard deviation 5 inches. What is the probability that an 18 year old man selected at random is between 70 and 72 inches tall? if random sample of twenty-nine 18 year old men is selected, what is the probability that the mean height x is between 70 and 72 inches? compare your answers to parts a and b. Is the probability in part b much higher? Why
Among all monthly bills from a certain credit card company, the mean amount billed was $465 and the standard deviation was $300. In addition, for 15% of the bills, the amount billed was greater than $1000. A sample of 900 bills is drawn. What is the probability that more than 150 of the sampled bills are for amounts greater than $1000? (Round the final answer to four decimal places.)
Business weekly conducted a survey of graduates for 30 top MBA programs. On the basis of the survey assume the means annual salary 10 years after graduation is $162,000. Assume the standard deviation is $40,000. Suppose you take a simply random sample of 39 graduates. For a single randomly selected graduate, find the probability that her salary is between $156,692.00 and $161,395.00. For a simple random sample of 39 graduates, find the probability that the average salary is between $156,692.00 and $161,395.00. Is the assumption of normal necessary? Yes, or No.
. According to one study, 15% of workers call in sick on their birthdays. A random sample of 11 workers is selected.a. What is the probability that at most 2 of the workers in the sample call in sick on their birthdays?b. Find the expected value and standard deviation (rounded to 2 decimal places)
Of all the students, 44% own an iPhone, with a standard deviation of .03 For that same sample of 400 students, what is the probability that at least 42% of them own an iPhone?