1 / 19

Accuracy

Accuracy. Rounding. Rounding is a way to shorten numbers that have too many decimal places E.g. You can round 1.45 to the nearest whole number This is 1 You can round to 1 decimal place This is 1.5. The Rules.

griffith-newton
Download Presentation

Accuracy

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Accuracy

  2. Rounding • Rounding is a way to shorten numbers that have too many decimal places • E.g. • You can round 1.45 to the nearest whole number • This is 1 • You can round to 1 decimal place • This is 1.5

  3. The Rules • You round (the last number we keep) up if the cut off number is 5 or above • E.g. • 1.5 to the nearest whole number is • 2 (5 was the cut off number) • The number we keep stays the same if the cut off number is under 5 • E.g. 1.44 to 1 d.p. • Is 1.4

  4. Try these; • Round these to the nearest whole number; • 14.85 • 30.6 • 79.5 • Round these to 1 d.p. • 4.682 • 29.950 • 50.97 • Round these to 2 d.p. • 73.592 • 0.3081 • 99.999

  5. Answers • 15 • 31 • 80 • 4.7 • 30 • 51 • 73.59 • 0.31 • 100

  6. Significant Figures • You can also round to significant figures • The rules are: • The first number is significant unless it is 0 • If it is 0 then the first number that isn’t 0 is the first significant figure • E.g. • What is the first significant figure for these numbers • 37.8 • 3 • 0.0538 • 5 • 0.002004 • 2 • What is 37.8 to 1 s.f.? • 40 (the 3 is rounded because of the 7)

  7. Try these • Round these to 2 s.f. • 657 • 499 • 0.05982 • Round these to 3 s.f. • 30303 • 89950 • 20785

  8. Answers • 660 • 500 • 0.06 • 30,300 • 90,000 • 20,800

  9. Estimating • When we estimate we usually round to 1 s.f. • E.g. What is 93 x 11 • 90 x 10 • 900 • What is 250 x 123 • 300 x 100 • 3,000

  10. Upper and Lower Limits • When we measure things they have been rounded up or down • E.g. A metre ruler is usually correct to 100.0 or 4 s.f. • It could be as big as: • 100.05 (this is 100.04999999 rounded to 5 s.f.) • You add 5 on to the end of the number for the upper limit • It could be as small as: • 99.95

  11. Try these; • Write down the upper and lowers limits for these: • The length of a pencil is 16cm correct to the nearest cm. • The weight of a box is 23.6 lbs correct to 1 d.p. • The weight of a baby is 4.2 kg correct to 1/10 of a kg • A journey took 75 minutes correct to the nearest minute

  12. Answers • 15.5 to 16.5 cm • 23.65 to 23.55 lbs • 4.25 to 4.15 kg • 75.5 minutes to 74.5 minutes

  13. Standard Form • This is a quick way of writing really long numbers e.g. a googol is 10 with 100 zeros after is but it can be written as 1 x 10100 • There are rules for using standard form; • It has to be written as y x 10z (this is the Exp button on your calculator) • Y has to be between 1 and 10 • The z tells you how many numbers come after the first number

  14. Really Big Numbers • 4 x 106 • 4,000,000 • 5 x 103 • 5,000 • 5.1 x 103 • 5,100 • 1.745 x 104 • 17,450 • 1.745 x 102 • 174.5 • 11 x 103 • This is written wrong and should be 1.1 x 104

  15. Try these; • Write these as ordinary numbers; • 3.05 x 102 • 49 x 106 • 5.7 x 103 • 7.48 x 109 • Write these in standard form; • 70,000 • 450,000 • 10,000,000,000 • 378,000,000

  16. Answers • 305 • This is written wrong 9it should be 4.9 x 107 • 5,700 • 7,480,000,000 • 7 x 104 • 4.5 105 • 1 x 1010 or 10 x 109 • 3.78 x 108

  17. Really Small Numbers • Standard form can be used for really small numbers like the mass of an atom or the size of a cell etc. • Decimals are written as 10-z • E.g. 7.8 x 10-3 • This is 0.0078 • There are three zeros before the 78

  18. Try these; • Write these as an ordinary number; • 2.6 x 10-3 • 5.7 x 10-5 • 9.82 x 10-4 • Write these numbers in standard form; • 0.006 • 0.035 • 0.00056 • 0.0006082

  19. Answers • 0.0026 • 0.000057 • 0.000982 • 6 x 10-3 • 3.5 x 10-2 • 5.6 x 10-4 • 6.082 x 10-4

More Related