Q1. If the probability of an event is 0.10, what are the odds for the event occurring?

A)   One to nine.

B)   One to ten.

C)   Nine to one.

Q2. At a charity fundraiser there have been a total of 342 raffle tickets already sold. If a person then purchases two tickets rather than one, how much more likely are they to win?

A)   1.99.

B)   2.10.

C)   0.50.

Q3. If the probability of an event is 0.20, what are the odds against the event occurring?

A)   Four to one.

B)   One to four.

C)   Five to one.

答案和详解如下：

Q1. If the probability of an event is 0.10, what are the odds for the event occurring?

A)   One to nine.

B)   One to ten.

C)   Nine to one.

Correct answer is A)

The answer can be determined by dividing the probability of the event by the probability that it will not occur: (1/10) / (9/10) = 1 to 9. The probability of the event occurring is one to nine, i.e. in ten occurrences of the event, it is expected that it will occur once and not occur nine times.

Q2. At a charity fundraiser there have been a total of 342 raffle tickets already sold. If a person then purchases two tickets rather than one, how much more likely are they to win?

A)   1.99.

B)   2.10.

C)   0.50.

Correct answer is A)

If you purchase one ticket, the probability of your ticket being drawn is 1/343 or 0.00292. If you purchase two tickets, your probability becomes 2/344 or 0.00581, so you are 0.00581 / 0.00292 = 1.99 times more likely to win.

Q3. If the probability of an event is 0.20, what are the odds against the event occurring?

A)   Four to one.

B)   One to four.

C)   Five to one.

Correct answer is A)

The answer can be determined by dividing the probability of the event by the probability that it will not occur: (1/5) / (4/5) = 1 to 4. The probability against the event occurring is four to one, i.e. in five occurrences of the event, it is expected that it will occur once and not occur four times.

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