IASSC Certified Lean Six Sigma Green Belt (ICGB) — Question 4

Due to excessive pollution, GREEN Solutions Inc. is considering subsidizing public transportation to work for its employees. According to the manager it takes an average weekday commute of 39 minutes with a Standard Deviation of 7 minutes for the employees to get to work while they use their personal vehicles for their office commute while the management set a policy of not more than 40 minutes for their daily one-way commute. A survey conducted one day on 70 employees showed an average of 34 minutes commuting time using the metro public transportation system with a Standard Deviation of 21 minutes. Assuming a Normal
Distribution for the commute times by either personal or public transportation, which of these is true?

Answer options

• A. The probability that they would arrive on time using personal vehicles is much higher than using the metro public transportation system (MPTS)
• B. The probability that they would arrive on time using the MPTS is much higher than using their personal vehicles
• C. The two probabilities are about the same excepting in one case the consistency is higher than the other
• D. We need to compile more data around weekends to incorporate for traffic differences
• E. When Standard Deviation is higher the probability goes down and so the MPTS is worse

Correct answer: B

Explanation

The correct answer is B because the average commute time using the MPTS is significantly lower than the threshold of 40 minutes, while the personal vehicle average is close to that limit. This suggests that employees are more likely to arrive on time using the MPTS. Options A and E incorrectly suggest that personal vehicles are better, while C and D do not accurately reflect the data given.