Question

A student attends a 50 marks test. No negative marks are given in the test. Find the probability that he scores 30 or 35.

Answer 1

Hint: In the question, it is given that in the test, there is no negative marking, so, a student can attain any mark ranging from 0 to 50 in the test in which maximum marks are 50.
Now, we can find the probability of the two cases that are given in the question where the student can get either 30 or 35 marks in the test.

Complete step-by-step answer:
The formula for calculating probability of an event is as follows
\[\Rightarrow P=\dfrac{Favourable\ outcomes}{Total\ outcomes}\]
As mentioned in the question, we have to find the probability of the student getting 30 or 35 marks in the test.
Now, first of all, we will calculate the total outcomes.
Now, as the student can attain any mark ranging from 0 to 50, hence, the total outcomes are numbers from 0 to 50 which is 51.
Now, for the favorable outcomes, we can see that the student can get either 30 or 35 marks, so, the favorable outcomes are 2.
Now, using the formula that is given in the hint to find the probability of the given event, we get the following
  \[\begin{align}
  & \Rightarrow P=\dfrac{Favourable\ outcomes}{Total\ outcomes} \\
 & \Rightarrow P=\dfrac{2}{51} \\
\end{align}\]
Hence, this is the probability for the required event.

Note: Another method of doing this question is as follows
Now, we can also calculate the individual probabilities of the events where the student gets 30 marks and where the student gets 35 marks.
Then, as they are connected with an ‘or’, hence, we can add the two separate probabilities and hence, we will get the same answer.