Page 68 - Basic College Mathematics with Early Integers

S E C T ION 1. 5 I ROUNDING AND ESTIMATING 45

Three of the given calculator answers below are incorrect. Find them by estimating each sum.

47. 463 + 219 602 48. 522 + 785 1307
Estimation is useful to check for
incorrect answers when using a calculator. For
49. 229 + 443 + 606 1278 50. 542 + 789 + 198 2139 example, pressing a key too hard may result in
a double digit, while pressing a key too softly
may result in the digit not appearing in the
display.
51. 7806 + 5150 12,956 52. 5233 + 4988 9011

Objective Solve each problem by estimating. See Examples 6 and 7.

53. An appliance store advertises three refrigerators on 54. Suppose you scored 89, 97, 100, 79, 75, and 82 on your
sale at $899, $1499, and $999. Round each cost to the biology tests. Round each score to the nearest ten to
nearest hundred to estimate the total cost. estimate your total score.

55. The distance from Kansas City to Boston is 1429 56. The Gonzales family took a trip and traveled 588, 689,
miles and from Kansas City to Chicago is 530 miles. 277, 143, 59, and 802 miles on six consecutive days.
Round each distance to the nearest hundred to Round each distance to the nearest hundred to
estimate how much farther Boston is from Kansas estimate the distance they traveled.
City than Chicago is.

57. The peak of Mt. McKinley, in Alaska, is 20,320 feet 58. A student is pricing new car stereo systems. One
above sea level.The top of Mt. Rainier, in system sells for $1895 and another system sells for
Washington, is 14,410 feet above sea level. Round $1524. Round each price to the nearest hundred
each height to the nearest thousand to estimate the dollars to estimate the difference in price of these
difference in elevation of these two peaks. (Source: systems.
U.S. Geological Survey)

59. In 2008, the population of Joliet, Illinois, was 60. Round each distance given on the map to the nearest
142,702, and the population of Evanston, Illinois, ten to estimate the total distance from North Platte,
was 75,543. Round each population to the nearest Nebraska, to Lincoln, Nebraska.
ten-thousand to estimate how much larger Joliet was
than Evanston. (Source: U.S. Census Bureau)
Omaha
281
North Platte
80
64 miles 41 miles
133 miles Lincoln
Lexington
Evanston Kearney
Chicago
136
Joliet
80
Nebraska
55
74 Peoria
57
Bloomington
Champaign
Springfield
57
55
70
64
57