1. Elena has a bag which contains 7 toffees, 4 mints and 2 chocolates.
Elena picks one of these sweets.
What is the probability that she chooses a:
a) mint b) mint or toffee c) mint or chocolate
2. 24 people come for a job interview.
9 of these people wear glasses and 4 of them have contact lenses.
Find the probability that the person chosen for the job:
a) has contact lenses
b) wears glasses
c) does not wear glasses or contact lenses
3. A dice is thrown 120 times.
How many times would you expect to get a:
a) 3 b) 5 c) 4 or 5 d) square number
4. The probability of Anu getting up before 11 a.m. on a Saturday
morning is 1/4. What is the probability of Anu not getting up before
11 a.m. on a Saturday morning?
5. Ahmed has some coins in his pocket. He has 5c, 10c and 50c coins. The
probability of choosing a 5c coin is 0·65. The probability of choosing
a 10c coin is 0·2.
a) What is the probability of choosing a 50c coin?
b) What is the probability of choosing a 10c coin or a 50c coin?
6. A bag contains 8 blue discs and 3 green discs.
One disc is removed at random then replaced.
Another disc is then removed.
a) Copy and complete the tree diagram to show all the outcomes.
Find the probability that:
b) Both discs are blue.
c) Both discs are green.
d) One disc is blue and one disc is green
7. A spinner is spun three times.
a) Copy and complete the tree diagram to show the probability of
getting a ‘two’.
b) Find the probability that the spinner lands on:
i) 3 two’s
ii) no two’s
iii) at least one ‘two’
8. There are 3 males and 5 females in a family of 8 people.
Two of the family members are chosen at random.
a) Copy and complete the tree diagram. Find the probability that:
b) Both people are female.
c) Exactly one person is female.
9. A bag contains 7 green counters and 3 purple counters. A counter is taken at random and its color noted.
The counter is not returned to the box.
Then a second counter is taken at random and its color noted.
It also is not returned to the box.
Finally a third counter is taken at random, and its color noted.(without replacement)Work out the probability that
i)all three counters are purple
ii)exactly one of the three counters is purple
iii)at least one of the three counters is purple
10. The probability of John doing more than 2 hours homework on a
Thursday evening is 0·6. If he does more than 2 hours homework, the
probability of seeing friends later that evening is 0·25. If he does 2 hours
or less homework, the probability of seeing friends later that evening is 0·7.
a) Draw a tree diagram to represent the above information.
b) Find the probability that John will see friends later that evening.
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