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A survey of 60 people found 40 people liked lemonade and 30 liked cola. Two people said they disliked both.
If one person is chosen at random what is the probability that this person;
a) likes lemonade
b) likes lemonade only
c) likes cola
d) likes both lemonade and cola
e) does not like lemonade
f) likes lemonade or cola
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From the condition, 40 people like lemonade, 30 like cola, and 60-2 = 58 like lemonade or cola.
It implies that (40+30) - 58 = 12 like both lemonade and soda.
// See the lesson referred at the end of my post to get understanding why it is so.
Then 40-12 = 28 like lemonade only, and 30-12 = 18 like cola only.
Now you can answer all questions:
If one person is chosen at random what is the probability that this person
a) likes lemonade = .
b) likes lemonade only = .
c) likes cola = .
d) likes both lemonade and cola = .
e) does not like lemonade = = .
f) likes lemonade or cola = .
All questions are answered.
For details and better understanding see the lesson
- Counting elements in sub-sets of a given finite set
in this site.