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Measurements. Description and Measurement Chapter 2:1 Pages 42-49. Measurement. A way to describe the world with numbers Answers questions such as how long, how much, or how far. Estimation. A rough measurement of an object You use prior knowledge to help you with an estimation
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Measurements Description and Measurement Chapter 2:1 Pages 42-49
Measurement • A way to describe the world with numbers • Answers questions such as how long, how much, or how far.
Estimation • A rough measurement of an object • You use prior knowledge to help you with an estimation • Comparison is a good way to create an estimation • Used to check if your answer is reasonable • Use the word “about”
Precision and Accuracy • Precision is a description of how close measurements are to each other …The SMALLER the measure the MORE precise • EX: a second hand is more precise than a minute hand • Accuracy is when you compare a measurement to a real, actual, or accepted value. • EX: a watch which is not set correctly is NOT accurate
Rounding • If the digit to the right is 0,1,2,3, or 4, the digit being rounded stays the same • If the digit is 5,6,7,8, or 9, the digit rounded increases by 1 • The digits to the right of the digit being rounded to are deleted if they are also to the right of the decimal. If they are to the left of the decimal, they are changed to zero. How we would round to the tens place? • 1579.254 • 28.888 • 17359.8882
Rounding Examples Round 217 to the nearest hundred Round 800 to the nearest hundred Round 564 to the nearest ten Round 295 to the nearest ten Round 725 to the nearest ten Round 959 to the nearest hundred Round 252 to the nearest ten Round 618 to the nearest hundred Round 928 to the nearest ten Round 732 to the nearest hundred Round 163 to the nearest ten Round 21 to the nearest ten
Significant Digits The number of digits that truly reflect the precision of the number are called significant figures. The Rules are as follows:
Mrs. Schremp Note To Self: Copy previous slide onto a notebook and do examples.
Rules for Sig. Figs. • For multiplication and division, you determine the number of sig figs in each number of your problem. The sig figs of your answer are determined by the number with the fewest digits. • EX: 6.14 X 5.6=34.384 • For addition and subtraction, you determine the place value of each number in your problem. The sig figs of the answer are determined by the number that is least precise. (using tens, hundredths, etc.) • EX: 6.14 + 5.6=11.74