91Ó°ÊÓ

A measure used to determine the occurence possibility of events is identified as probability. The measure is computed as quotient of two counts; favorable and total.

Mathematically, it is given as:

$P\left(A\right)=\frac{\text{Number}\text{of}\text{favorable}\text{outcomes}}{\text{Total}\text{number}\text{of}\text{outcomes}}$

a.

The total number of days in a year is 365.

The number of days on which the randomly selected person can be born is 1; October 18.

The probability of event E, i.e.,the person was born on October 18 is:

$P\left(E\right)=\frac{1}{365}$

Thus, the probability that the randomly selected person has birthday on October 18 is$\frac{1}{365}$.

b.

The total number of days in a year is 365.

The number of days on which the randomly selected person can be born is 31.

The probability of event F, i.e., the person was born in October is:

$P\left(F\right)=\frac{31}{365}$

Thus, the probability that the randomly selected person has birthday in October is$\frac{31}{365}$.

c.

Subjective probability is the estimate of probability computed using information from personal judgment.

As the population of US adults is large, the total number of outcomes becomes large. Consequently, the probability of finding an American adult who knows that October 18 is National Statistics Day in Japan is small.

It can be estimated that the probability would be less than or equal to 0.01.

d.

An unusual event is one that occurs with a probability less than or equal to 0.05. As the subjective estimate is lesser than 0.01, the event is unlikely to occur.

Thus, there are fewerchances that a randomly selected American would know October 18 as the National Statistics Day in japan.