6. The life of a semiconductor laser at a constant power is normally distributed with a mean of7000 hours and a standard deviation of 600 hours.(a) What is the probability that a laser fails before 5000 hours?(b) What is the life in hours that 95% of the lasers exceed?(c) If three lasers are used in a product and they are assumed to fail independently, what is theprobability that all three are still operating after 7000 hours?

GivenMean(μ)=7000standard deviation(σ)=600

Answered: 6. The life of a semiconductor laser at…

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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11. The amount of time that a drive-through bank teller spends on a customer is a random variable with a mean μ = 6.4 minutes and a standard deviation o=3.5 minutes. If a random sample of 49 customers is observed, find the probability that their mean time at the teller's window is (a) at most 5.6 minutes; (b) more than 7.4 minutes; (c) at least 6.4 minutes but less than 7.0 minutes. Click here to view page 1 of the standard normal distribution table.¹ Click here to view page 2 of the standard normal distribution table.² (a) The probability that the mean time is at most 5.6 minutes is (Round to four decimal places as needed.) (b) The probability that the mean time is more than 7.4 minutes is (Round to four decimal places as needed.) (c) The probability that the mean time is between 6.4 minutes and 7.0 minutes is (Round to four decimal places as needed.)
2. An automobile battery manufacturer claims that its midgrade battery has a mean life of 50 months with a standard deviation of 6 months. Suppose the distribution of battery lives of this particular brand is approximately normal. On the assumption that the claims are true, find the probability that a randomly selected battery of this type will last less than 48 months. (Use the software link for every question) (a) Let X = number of months a battery will last. Write the question above in terms of this variable X (b) Find the probability that a single battery of this type will last less than 48 months. (c) Find the probability that the mean of a random sample of 36 batteries will be less than 48 months. (d) Why do you think the values from part (b) and part (c) are different? Explain.
A standardized exam’s score are normally distributed. In a recent year, the mean test score was 1477 and the standard was 315. The test scores of four students selected at random 1860 1230, 2160, and 1360. Find the Z- score that correspond to each value and determine wether any of the values are unusual. The Z-score for 1860 is-The Z-score for 1230 is-The Z-score for 2160 is-The Z-score for 1360is-
Suppose that the average height of men in the United States is approximately normallydistributed with a mean of approximately 70 inches and a standard deviation ofapproximately 4 inches. (a) If you take a sample of 4 men, find Pr {68 ≤ Y̅ ≤ 73}, the probability that the sample mean Y̅ will be between 68 and 73 inches. (b) If you take a sample of 16 men, find Pr {68 ≤ Y̅ ≤ 73}, the probability that the sample mean Y̅ will be between 68 and 73 inches. (c) If you take a sample of n men where n > 16, which one of the following is true? (circle one of the three statements.)Pr{68 ≤ Y̅ ≤ 73} > the probability that you found in (b)Pr{68 ≤ Y̅ ≤ 73} = the probability that you found in (b)Pr{68 ≤ Y̅ ≤ 73} < the probability that you found in (b)
a) The failure time (T) of an electronic circuit board follows an exponential distribution with failure rate 2 = 10-4 /h. What is the probability that ) circuit board will fail before 1,000 hrs (ii) circuit board will survive at least 10,000 hrs.? b) A study is conducted to determine the relationship between a driver's age and the number of accidents
5. Suppose the time spent by a randomly selected student at a campus computer laboratory has a gamma distribution with mean 20 min and variance 80 min². (a) What are the values of a and B? (b) What is the probability that a student spends between 20 and 40 min at the laboratory? (c) Only 1% of students will spend more than how many minutes at the laboratory?
Suppose a random sample of 25 students is selected from a community college where the scores on the final exam (out of 125 points) are normally distributed having mean equal to 112 and standard deviation equal to 4. Find the probability that the sample mean deviates from the population mean µ = 112 by no more than 3.
The lifespans of light bulbs are known to follow an exponential distribution. The exponential distribution, often denoted exp(β), is characterized by a single mean parameter β. The exponential distribution has a unique property that its standard deviation is equal to its mean. Suppose you order 100 light bulbs known to each have lifespans (in years) distributed according to exp(4). What is the probability that the average lifespan of your 100 light bulbs exceeds 5 years? (Using R it possible)
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The average amount of time until a car accident on a particular 60 mile stretch of road is 30 minutes. Assume(unreasonably) that car accidents are independent, the time to a car accident is exponentially distributed, and that two accidents cannot occur at the same time. a. What is the probability of a car accident occurring in the first hour?b. What is the probability of a car accident occurring between 15 and 45 minutes? c. What is the variance of the time until a car accident occurs? If a car accident has not happened in 2 hours, what is the probability it will happen in the next hour? DO NOT USE THE INTEGRATION METHOD PLEASE.

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