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Estimation

Estimation. By Dr. Hong Zhang For Freshman Engineering Clinic. Purposes. To save cost To save time To give a big picture To make a tentative decision To be the first step for future action. Errors. Based on the knowledge in hand Make reasonable assumptions

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Estimation

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  1. Estimation By Dr. Hong Zhang For Freshman Engineering Clinic

  2. Purposes • To save cost • To save time • To give a big picture • To make a tentative decision • To be the first step for future action

  3. Errors • Based on the knowledge in hand • Make reasonable assumptions • 10%~20% or even higher error is normal • New information can and should be used to refine the estimate

  4. Example • Estimate how many chicken are consumed every year in US

  5. Process of Estimate • Collect Data: Population of US is 300 million • Make Assumption: • Average family will consume 2 chicken per month • Average family will have 3 members • Calculation: 2/month * 12 month * (300million/3) =2400 million • Estimate: We consume 2.4 billion chicken per year • Sometime we round up: We consume3 billion chicken per year

  6. Example • Gasoline Consumption To Travel Home • Estimate the amount of gasoline used by Iowa States University students in traveling home and returning during the next Thanksgiving.

  7. Assumptions • Only gasoline for automobiles is considered. Fuel for airplane or train is not considered. • 10% students fly home. The trip to the airport will be by automobile. • Average carpool level is 2 students/car. • Average auto mileage is 20 miles/gallon. • Travel distance will be estimated to be as medium of 50, 150, 250, 350, 450 miles one way. Longer distances will be assumed to fly.

  8. Collected Data • Total 26,500 students in ISU. • Cost of gasoline: $3.59/gal • Distance to airport is 45miles.

  9. Calculations: Travel Distance Estimate

  10. Mileage Total

  11. Total Cost • Gasoline Consumption: (3,166,750miles)/(20miles/gal) = 158,337.5 gal = 1.6*105gal • Gasoline Cost: 158,337.5 gal * $3.59/gal = $568,431.43 = $570k = $0.57 MM

  12. Exercise 1 • Estimate the amount of gasoline used by Rowan University students in traveling home and returning during the next Thanksgiving.

  13. Assumptions • Only gasoline for automobiles is considered. Fuel for airplane or train is not considered. • No student will fly. Assume all students are local or regional. • Average carpool level is 2 students/car. • Average auto mileage is 25 miles/gallon. • Travel distance will be estimated to be as medium of 50, 150, 250, 350 miles one way.

  14. Collected Data • Total 11,392 students in Rowan University. • Cost of gasoline: $2.47/gal (estimate) • Distance to airport is 26 miles.

  15. Calculations: Travel Distance Estimate

  16. Mileage Total

  17. Total Cost • Gasoline Consumption: ( miles)/(25miles/gal) = • Gasoline Cost: gal * $2.50/gal = $

  18. Exercise 1 • Estimate the amount of gasoline used by your class in traveling home and returning during the next Thanksgiving.

  19. Assumptions • Only gasoline for automobiles is considered. Fuel for airplane or train is not considered. • No student will fly. Assume all students are local or regional. • Average carpool level is ? students/car. • Average auto mileage is 25 miles/gallon. • Travel distance will be estimated to be as medium of 50, 150, 250, 350 miles one way.

  20. Collected Data • Total 20 students in your class. • Cost of gasoline: $2.47/gal

  21. Data: Travel Distance

  22. Total Cost • Gasoline Consumption: ( miles)/(25miles/gal) = • Gasoline Cost: ( gal) * $2.47/gal = $

  23. Exercises • Estimate the number of books you will read in your lifetime. • Estimate the total amount of time, mileage and cost you will spend commuting to and from class for this semester. • Estimate the amount of total time spent by the members of this class studying for the class this week. • Estimate the total steps you walk every day and every year. • Estimate the cost of all the food you will consume this semester.

  24. Optional • Estimate the number of gallons of water in Esby pool. • Estimate the paint to paint the outside wall of Rowan Hall. • Estimate how much water you will drink and how much food you will eat in your lifetime

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