1.2 Estimation Techniques 11 Using either estimate, we find the bill of $69.51 is quite high. Therefore, Raj should check the bill carefully before paying it. Adding the prices of all six items gives a true cost of $55.77. 7 Now try Exercise 29 Example 3 Select the Best Estimate The numbers of bushels of grapes produced at a vineyard are 71,309 Cabernet Sauvignon, 123,879 French Colombard, 106,490 Chenin Blanc, 5960 Charbono, and 12,104 Chardonnay. Select the best estimate of the total number of bushels produced by the vineyard. a) 500,000 b) 30,000 c) 300,000 d) 5,000,000 Solution Following are suggested roundings. On the left, the numbers are rounded to thousands. For a less accurate estimate, round to ten thousands, as illustrated on the right. Round to the Nearest Thousand Round to the Nearest Ten Thousand 71,309 → 71,000 71,309 → 70,000 123,879 → 124,000 123,879 → 120,000 106,490 → 106,000 106,490 → 110,000 5,960 → 6,000 5,960 → 10,000 12,104 → 12,000 12,104 → 10,000 319,000 320,000 Either rounding procedure indicates that the best estimate is (c), or 300,000. 7 Now try Exercise 35 m Gateway Arch in St. Louis, MO. Example 4 Using Estimation in Calculations The Travis family traveled 1276 miles from their home in Portland, Maine, to the Gateway Arch in St. Louis, Missouri. a) If their trip took 19.9 hours of driving time, estimate the average speed, in miles per hour, that their car traveled. b) If their car used 52 gallons of gasoline, estimate the average gas mileage of their car, in miles per gallon. c) If the cost of gasoline averaged $3.95 per gallon, estimate the total cost of the gasoline used. Solution a) To estimate the average miles per hour, divide the number of miles by the number of hours. 1276 19.9 Round these numbers to obtain an estimate. 1300 20 65 = Therefore, the car averaged about 65 miles per hour. b) To estimate the average gas mileage, divide the number of miles driven by the number of gallons of gasoline used. 1276 52 Amolson7/Shutterstock
RkJQdWJsaXNoZXIy NjM5ODQ=