Number and Arithmatic

Page 1

Grade D

Rounding - Numbers round up if the next digit is 5 or more

104.458

a 2dp -104.46

b 1dp - 104.5

c the nearest 10 - 100

d the nearest 1000 - 0

Significant figures- When rounding to a number start counting at the first non zero

Round to two significant figures

16.668 - 17 to 2sf

14559 - 15000 to 2sf

0.000675 - 0.00068 to 2sf

Round 0.0724591 to 3 significant figures (s.f.)

= 0.0725

Round 0.2300105 to 4 significant figures (s.f.)

= 0.2300

19.4 / 0.0437

Round to 1sf

20/0.04 (20*100) / (0.04 * 100) 2000/4 = 500

386062 × 0.007243?

Round to 1sf

400000 * 0.007000

2800

Grade B/A

Upper and Lower Bounds-Measurements are not exact.Theeir accuracy depends on the measuring equiptment and human.

The mass of a meteorite is given as 235.6

Find the lower and upper bounds

answer

The mass is given correct to the nearest 0.1

Lb= 235.55

Ub= 235.65

The mass is 234.55

A student was asked to give the upper and lower bounds for a measurement given as 4.5 seconds.The lower bound is 4.45 and the upper bound is 4.5499999

What is wrong with the answer

The upper bound is not a possible value of the measurement.

Find the upper and lower bounds

a 6.7m

lb=6.65 ub= 6.75

b 7.74

lb= 7.735

ub= 7.745

Find the maximum and minimum possible total weight of

a 12 boxes each of which weighs 14kg to the nearest kg

12*14 = 168

lb = 167.5

ub = 168.5