Examples of probability

The concept of probability is not a foreign to health workers. For
example we may hear a physician say that a patient has 50-50
chance surviving from a certain operation, or physician may say
that a patient has 95% a particular disease. Most people express
probabilities in terms of percentages. But, it is more convenient
to express probabilities as fractions. Thus, we may measure the
probability of the occurrence of some event by a number
between 0 and 1.
The more likely the event, the closer the number is to one. An
event that can’t occur has a probability of zero, and an event that
is certain to occur has a probability of one.


Suppose we pick a person at random from this sample.
1-The probability that this person will be diabetic .
2. 1-The probability that this person will be normal
3-The probability that this person will be diabetic (D) when the selected person was male (conditional probability )?
3-The probability that this person will be diabetic and male (joint probability)?
4-The probability that this person is male (M) or normal(H)?
5. P(M or F).
Suppose we pick a person at random from this sample.
1-The probability that the child will be > 3 Kg birth weight .
2. 1-The probability that child will be girl
3-The probability that child will be boy when the selected birth weight < 2.5 Kg?
3-The probability that the child will be girl and birth weight 2.5 - < 3 Kg ?
4-The probability that the child is boy or > 3 Kg birth weight ?
5. P(B or G).