Starter

1
Starter
If 4 oranges cost 3.60, how much will nine
oranges cost. 1 orange 90 cents 9 oranges
8.10 It takes 5 men 4 hours to chop up some
firewood. How long would it take two men? 1 man
20 hours 2 men 10 hours
2
Starter
In a duck egg the ratio of yolk weight to
egg-white weight is 32. If the egg-white weighs
14g, calculate the weight of the yolk. Yolk
21g The ratio of weight lifted to their own body
weight for a male Olympic-class weightlifter can
sometimes exceed 52. If a weightlifter weighs
80kg, what weight would he aim to exceed? Aim to
lift 200kg
3
Note 9 Significant Figures

• The number of significant figures a number has,
  is the total number of digits that represent it.
• Example 3147 (4 sf)

4

• Zeros are significant when they are
• inbetween other numbers
• both at the end of a number and after the decimal
  point
•  
• Examples 9.703
• 7.40

(4 sf)
(3 sf)

• Zeros are not significant when they are
• at the front of a number
• at the end of a number with no decimal point
•  
• Examples 0.036 24000

(2 sf)
(2 sf)
5
Note 10 Rounding

• To round a number to a given number of decimal
  places/significant figures
• Underline the number of decimal place/significant
  figures required
• Look at the next digit, if it is
• less than 5, drop all numbers not underlined
• 5 or more, then add one to the last digit
  underlined and drop all other numbers
• For significant figures, zeros may be needed as
  place holders

6
  Examples 3.8194 (2 dp) 4368 (2
sf) 12.895 (2 dp) 0.0546 (1 sf)
(3.82)

(4400)
(12.90)
(0.05)
7
Note 11 Standard Form

• Very large and very small numbers are written in
  standard from.
• Example 3.14 102

8
Standard Form Number  Move the
decimal point to the right if the power is
positive and to the left if the power is
negative. Examples 5.364 102 2.46 10-1

536.4
0.246
Number Standard Form Move
the decimal place to after the first significant
figure. Find the value of the power. Examples
5812 0.019
5.812 103
1.9 10-2
9
Page 25 Exercise P Page 27 Exercise R and S