Chapter 1 Lesson4

Physical Science

 There are 2 kinds of numbers: ◦ Exact: the amount of money in your account. Known with certainty.

◦ Approximate: weight, height—anything MEASURED. No measurement is perfect.

 When a measurement is recorded only those digits that are dependable are written down.

◦ If you measured the width of a paper with your ruler you might record 21.7cm. To a mathematician 21.70, or is the same.

 cm to a scientist means the measurement is accurate to within one thousandth of a cm.

 If you used an ordinary ruler, the smallest marking is the mm, so your measurement has to be recorded as 21.7cm.

 Rule: All digits are significant starting with the first non- zero digit on the left.

 Exception to rule: In whole numbers that end in zero, the zeros at the end are not significant.

 7  40  0.5   7 x 10 5  7,000,000 11 11 11 11 11 11

 2 nd Exception to rule: If zeros are sandwiched between non-zero digits, the zeros become significant.

 3rd Exception to rule: If zeros are at the end of a number that has a decimal, the zeros are significant.

 3rd Exception to rule: These zeros are showing how accurate the measurement or calculation are.

 1.2  2100   4.00   7,083,000,00 0 22 22 44 33 33 44

 3401  2100   5.00   8,000,050,00 0 44 22 55 33 33 66

 Rule: When adding or subtracting measured numbers, the answer can have no more places after the decimal than the LEAST of the measured numbers.

 2.45cm + 1.2cm = 3.65cm,  Round off to = 3.7cm  7.432cm + 2cm = round to  9cm

 Rule: When multiplying or dividing, the result can have no more significant figures than the least reliable measurement.

 cm x 2.45cm = cm 2  Round to  139cm 2  75.8cm x 9.6cm = ?

Have Fun Measuring and Happy Calculating!

1) = _______ 2) = _______ 3) = ____ 4) = _______

1) = ) = ) = ) = 16.9

1) 410 ÷ 2.76 = __________ 2) 0.9 x x 1000 = _____ 3) 6000 ÷ 5.5 = __________ 4) 2.13 x 58 = __________

1) 410 ÷ 2.76 = 150 2) 0.9 x x 1000 = 4 3) 6000 ÷ 5.5 = 1,000 4) 2.13 x 58 = 120

Listen to the song Click below

1) 7, 8, 9, 6, 4, 6, 2, 7, 5 Mean ____ Median ____ Mode ___________ Range ____ Mean 6 median 6 mode 6 7 range 7

2) 8, 3, 3, 8, 4, 7, 2, 2, 8 Mean ____ Median ____ Mode ___________ Range ____ Mean 5 Median 4 Mode 8 Range 6

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