Page 424 - Math Smart - 7

On this probability scale,
• an event that is impossible has a probability of 0.
• an event that is certain has a probability of 1.
• all other probabilities on this scale are between 0 to 1.

Probabilities can also be written as decimals or percentages,
impossible unlikely equally likely likely certain
unlikely

0.25 0.5 0.75
25% 50% 75% 100%
4 ''=1
0 e e

Use the words impossible,
unlikely, equally likely,
likely or certain to describe
the probability of each The table shows a netbal! coach's estimates of the team's chances of winning their
outcome. matches against three schools.
a) The day which follows
School Chance of winning
Wednesday is a Friday.
Rose High 0.1
b) The next 60 babies
born in London will all Crossroads High 90%
be boys. New Horizons High 1
2
The next month will
have at least 28 days. a) Which school is the team most unlikely to beat?
d) I will be 4 metres tall b) Write this probability as a percentage.
next year.
a) Which school is the team almost certain to beat?
e) You will be one year
b) Write this probability as a decimal.
older this time next
year.
a) Which school does the team have an even chance of scoring a win
f) Rolling a number against?
smaller than six on a
b) Write this probability as a percentage.
die.
0 Write this probability as a decimal.
g) Rolling a number
Solution
smaller than seven on a
die. 0 1
h) A coin will land tails if 0% 50% 100%
it is tossed. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
i) A drawing pin will land 1 L _l_ -J I I I I -I
point up if it drops on
the floor.
Rose High New Horizons High Crossroads High
j) It will snow somewhere
a) Rose High School.
in Russia next winter.
The probability of the team beating Rose High School is 0.1. This is close
to 0 on the probability scale which means the team is unlikely to beat
Rose High School.

^20 UNIT 18 robabflity