Sales delay is the elapsed time between the manufacture of a product and its sale. According an article it is quite common for investigators to model sales delay using a lognormal distribution. particular product, the cited article proposes this distribution with parameter values u = 2.08 and a? = 0.04 (here the unit for delay is months).

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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Please help me answer questions c,d,e, and f

Sales delay is the elapsed time between the manufacture of a product and its sale. According to an article, it is quite common for investigators to model sales delay using a lognormal distribution. For a particular product, the cited article proposes this distribution with parameter values \( \mu = 2.08 \) and \( \sigma^2 = 0.04 \) (here the unit for delay is months).

**Questions and Solutions:**

(a) What are the variance and standard deviation of delay time? (Round your answers to two decimal places.)
- Variance: \( 2.72 \) months\(^2\)
- Standard deviation: \( 1.65 \) months

(b) What is the probability that delay time exceeds 12 months? (Round your answer to four decimal places.)
- Probability: \( 0.0217 \)

(c) What is the probability that delay time is within one standard deviation of its mean value? (Round your answer to four decimal places.)
- Probability: [Blank space for answer]

(d) What is the median of the delay time distribution? (Round your answer to two decimal places.)
- Median: [Blank space for answer] months

(e) What is the 99th percentile of the delay time distribution? (Round your answer to two decimal places.)
- 99th percentile: [Blank space for answer] months

(f) Among 10 randomly selected such items, how many would you expect to have a delay time exceeding 7 months? (Round your answer to three decimal places.)
- Expected items: [Blank space for answer]

This set of questions involves the application of statistical methods to model the delay time using a lognormal distribution. The variance and standard deviation have been given, along with the probability that delay time exceeds a certain threshold. The activity requires further calculations to complete all answers, which can enhance understanding of probability distributions in practical scenarios.
Transcribed Image Text:Sales delay is the elapsed time between the manufacture of a product and its sale. According to an article, it is quite common for investigators to model sales delay using a lognormal distribution. For a particular product, the cited article proposes this distribution with parameter values \( \mu = 2.08 \) and \( \sigma^2 = 0.04 \) (here the unit for delay is months). **Questions and Solutions:** (a) What are the variance and standard deviation of delay time? (Round your answers to two decimal places.) - Variance: \( 2.72 \) months\(^2\) - Standard deviation: \( 1.65 \) months (b) What is the probability that delay time exceeds 12 months? (Round your answer to four decimal places.) - Probability: \( 0.0217 \) (c) What is the probability that delay time is within one standard deviation of its mean value? (Round your answer to four decimal places.) - Probability: [Blank space for answer] (d) What is the median of the delay time distribution? (Round your answer to two decimal places.) - Median: [Blank space for answer] months (e) What is the 99th percentile of the delay time distribution? (Round your answer to two decimal places.) - 99th percentile: [Blank space for answer] months (f) Among 10 randomly selected such items, how many would you expect to have a delay time exceeding 7 months? (Round your answer to three decimal places.) - Expected items: [Blank space for answer] This set of questions involves the application of statistical methods to model the delay time using a lognormal distribution. The variance and standard deviation have been given, along with the probability that delay time exceeds a certain threshold. The activity requires further calculations to complete all answers, which can enhance understanding of probability distributions in practical scenarios.
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