7BOBO-dHHHHHH-dH--) - -Zl`)xHH(FG(HH(d'@.x$----l>/:A-@y-- (8*-*0-@nd/C:.h9v -|!4 }DSETfMN5(M-L-T-Py--vPy-P,l4y--vy-/t y--v y--vyy- .lBy--vJy-<-vy--vNy--v y--v!y--v$y--v'gy--v)ay--v+2y--v-y--v.y-t-x2y--v@345NDEFGHIJKLfgh DEFGHIJKLMNOP$%&'()*+,-GHIrstuv%&'()*+,-./01234 !"#  7 8 9 : ;     ! hijklmnop'()*+,-hijklmnopqrstuvwxy!0@QbcEFGHIJKefgABrsDEFGHIJKefgCDEFGHIJ%&'()*+fghijkltuvwxyOPQRSmno    KLMNmnop !"#=>?hijkl !v!w!x!y!z!{!|!!!!!!!!!!!!!""#D#E#F#G#H#I#################$$$$$$$$$$$$$$$$%%&&& &!&"&#&$&`&a&b&c&d&e&&&&&&&&''''' '!'"']'^'_'`'a'b'c'd'e'f'g''''''''''''''''''''(F(G(H(I(J(K(((((()X)Y)Z)[)\)])^)_)`)a)))))))))))))*w*****+++++ +!+"+#+$+%+&+'+(+)+*+++,+-+.+/+0+1+2+++++++++,,,,=,>,?,@,A,,,,,,,,,,,,,,,,,,,,,,,----------------.'.(.).*.+.......................0b0c0000001N1O1P1Q1R1S1T111111111222222v2w2x2y2z2{2|223i3j3k3l3m3n3o3p3q3r3s3t3u3v3w3x3y3z33334l4m4n4o4p4q4444445555   L E P w x      - & 4               p i y   d K A B K D       S L N "     ! ! # $ &e '^ + + + , , -B -C -P -k -l - . . . / / / / 1 2 3! 3& -H-D-@ -<-8-4g-0g-,g-(#g-$'g- +g-/g-2h,-d UNIT 13: PRECISION, ACCURACY, and TOLERANCE EVEN QUESTIONS 2-40 2. A typical yardstick is marked in inches on one side and in centimeters on the other side. The inches are marked to the nearest 1/8 and the centimeters are marked to the nearest 0.1 cm. Which scale gives the more precise measurement? What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 4. Your normal body temperature is 98.6oF. What temperature is this in Celsius degrees? Show your answer with the same precision as the given temperature. Recall that Celsius= 5/9 x (Fahrenheit - 32oF) . What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 6. Seeds are normally purchased and sown by weight. Suppose you sample carrot seeds for a seed company and count out 1000 seeds that weigh 1.23 grams. a. What is the precision of your seed count? of your sample weight? b. What number of seeds per gram can you report? What number of seeds per ounce can you report? (Report your answer with the correct number of significant digits.) What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 8. To estimate the volume of lumber in a standing tree requires a measure of the diameter of the tree at breast height (dbh). To obtain this, you measure the circumference of the tree with a steel tape measure and divide by to get a diameter. Suppose you measure several tree circumferences, as listed below. Compute the diameter of each tree, and report it with the correct number of significant digits. Tree Circumference A 58 B 107 C 42 D 28 What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 10. As an entomologist, you examine fields for the cotton boll worm. If more than 6000 worms per acre are found, an insecticide treatment is needed. To estimate the number of worms per acre, all the plants on several short lengths of row will be examined. For 38-inch rows, there are a total of 13,756 row-feet per acre. Suppose you examine four 72-inch sections of rows (that is, 6 row-feet each), and count a total of 9 worms. a. Set up a proportion equating the ratio of worms counted to the number of  row-feet examined and the ratio of worms per acre to the number of row-feet per acre. Solve for the unknown number of worms per acre. (Report your answer with the correct number of significant digits.) b. Does this finding warrant an insecticide treatment? c. Suppose you found 10 worms. Repeat the calculations to find whether a treatment is needed. 12. Your business uses a solvent that is stored in 55-gallon drums. During your weekly inventory, you count 29 drums in the storage area. How many gallons of solvent should you report are in storage? What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 14. As a travel agent, you log the airline mileages traveled by your customers to qualify them for special discounts and awards. If a customer travels over 5,000 miles with a particular airline, he is eligible for an expense-paid weekend in Hawaii. A particular clients file shows the following travel mileages: Date Miles 2/12 480 3/21 720 3/28 250 4/15 900 4/20 160 6/2 1210 7/8 690 7/11 540 8/17 160 a. What is the apparent precision of the mileages shown above? b. What is the total of the mileages shown? (Report your answer to the correct precision.) Is this client eligible for the expense-paid weekend? What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 16. You consider a tract of property for a business development. The property is advertised as selling for $8 per square foot. Your interest is in the rectangular portion of the lot that includes a large oak tree. You pace off the section and estimate that it is 105 feet deep and 88 feet wide. a. What is the area of the section of the lot you measured? State your answer to reflect the precision of your measurements. b. Estimate the cost of this section, based on your measurements. What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 18. In a certain year, individuals in the United States paid about $227,000,000,000 in income tax. The estimated population was then 248,000,000. a. Identify the number of significant digits in each number given. b. What was the average amount of tax paid per person during this year? (Indicate the precision of your answer.) What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 20. You work for the city water department. A customer calls to ask how much less the water bill might be per month if the household were to wash one less load of clothes a week. You explain that the water meter is read to the nearest 100 gallons each month, and the customer is charged $1.66 per 1000 gallons. a. Assuming four weeks per month, how many gallons of water might the customer save? (Indicate the accuracy of your result.) b. About how much difference might this customer see in the monthly bill? c. What difference might this customer see in the total water costs for the year (assuming that conditions do not change)? What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 22. One of the flasks in your laboratory is labeled as 500 ml +/- 5%. It is graduated (marked) at 150 ml, 200 ml, 250 ml, and so on up to 500 ml. a. The tolerance of the 500-ml mark is +/- 5%. Is this an indication of the accuracy, or the precision of the marking? b. What are the upper and lower limits of the actual volume of the flask filled to the 500-ml mark? c. What is the tolerance interval of this filled flask? What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 24. If you are a medical technician, you may examine tissue samples or cultures under a microscope, with the aid of a microgrid slide. Such a slide is etched with a grid used to measure specimens. The distance between adjacent lines within a grid is 20 +/- 2 micrometers in the vertical direction, and in the horizontal direction is 100 +/- 2 micrometers. A portion of such a grid is shown below. a. Suppose you measure along the horizontal direction, and then along the vertical direction. Which measurement would you feel more confident about? Why? b. What is the stated accuracy of the grid lines in the horizontal direction? in the vertical direction? 26. The scale in the produce section of the grocery store has 16 divisions between each pound. The scale at the checkout displays the weight in pounds to two decimal places. a. What is the precision of the scale in the produce section? What is the precision of the scale at the checkout? Which is more precise? b. What is the greatest possible error of each scale? c. What can you say about the accuracy of the two scales? What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 28. A dieting guide describes the calorie content of 11.7 oz of lean beef rib roast as having 1456 calories. The kitchen scale you are using is calibrated to the nearest 1 oz. Your serving of roast measures about 6 oz. a. What is the precision of your scale? What is the greatest possible error of a measurement with this scale? b. What can you say about the accuracy of the two scales? What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 30. A portion of a weekly kitchen inventory is shown below. a. To perform a cost extension of the inventory, multiply the quantity by the price per unit quantity. Dont round the extensions yet. b. Examine the precision of the data in the inventory, particularly the quantities. How precise is each quantity? c. Should you round any of your extensions to reflect the significant digits and precision of the measurements? If so, which ones? 32. You need to calculate the total electrical power needs for a houses electrical wiring. Below is a list of the estimated needs. a. Choose the best answer to complete the following statement: Most of the wattages appear to be precise to the nearest 1) 1000 watts 2) 100 watts 3) 10 watts 4) 1 watt b. Compute the total of the wattages listed, and report the total with the correct precision. 34. A blueprint specification calls for a hole to be drilled 0.637 +/- 0.0005 in diameter. Is a drill bit making a 41/64 hole within the required tolerance? (Show your work.) What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 36. An oil refinery has 12 storage tanks. Each tank can store 250,000 gallons. If a barrel of oil is 42 gallons, how many barrels of oil can be stored at the refinery? (Indicate the precision of your answer.) What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating the answer(s). Your answer(s) are (make sure the units used are correct): 38. As you perform a lab analysis of a small metallic sphere, you need to determine whether the metal has a density closer to that of Metal A or Metal B. Metal A has a density of 2.71 g/cm3, and Metal B has a density of 2.67 g/cm3. A microbalance reports the mass of the sphere as 0.5274 g. Using a vernier caliper, you measure the diameter of the sphere as 0.72 cm. a. Compute the volume of the metallic sphere. (Dont round the answer yet.) b. Determine the density of the sphere by dividing its mass by its volume. Round to the correct number of digits, based on the measurements. c. Can you say whether the sphere is more likely Metal A or Metal B? Explain your decision. What are you looking for? What do you need to answer the question? Write out the methods that you will use to solve the problem and show your work in calculating t,he answer(s). Your answer(s) are (make sure the units used are correct): 40. Using a machinists rule you measure the thickness of the 1/2 metal bar stock and find that it is 33/64 thick. Using a micrometer, you obtain the reading shown below. a. What is the reading shown by the micrometer above? b. What is the precision of the metal rule, based on the reported bar stock thickness? What is the precision of the micrometer reading? Which device is more precise? c. What is the greatest possible error of the metal rule? of the micrometer? d. Suppose the specifications called for a bar stock that was 0.50 +/- 0.02. Based on your two measurements, is this bar stock within the upper and lower limits of the specification? DSET|(HDd->"9 *6*>"9DSET(H-9>96*=9DSETR -- -|-l   -Unit 13 Even Questions