Question

Martha wants to predict the probability of rain today based on the previous data. In the last 100 days, if it did not rain on 68 days, then what is the probability of today being a rainy day?

• A. $0.32$
• B. $0.16$
• C. $0.12$
• D. $0.68$

Answer 1

The correct option is A $0.32$

Sample space consists of all the 100 days for which the data is considered.
So, the number of elements in the sample space $=100$.
It has not rained on 68 days in the last 100 days.
The probability of not raining on a particular day$=\frac{\text{Number of days it did not rain}}{\text{Total number of days}}=\frac{68}{100}=0.68$
But the sum of all the probabilities raining and not raining on a particular day is $1$.
So, the probability of today being a rainy day $=1-0.68=0.32$