Question

In an absolutely hypothetical scenario and a cruel world, the professor is grading the students through the following model:

The students will receive a grade based on the outcome of drawing a ball from a bag.

Consider the bag containing 60 lottery balls, numbering from 1 to 60.

Additionally, each ball is either white or red; all the odd-numbered balls are white, and all the even-numbered balls are red. If a student draws a white ball, he/she will also be getting a free football ticket; if a student draws a red ball, the professor will buy the student ice cream.

The students are to draw one ball from the pool. Below is the scheme of the grade with their respective necessary outcome:

Outcome – Corresponding

Grade :

60-44 A

43-30 B

29-18 C

17-8 D

7-1 F

What is the probability of getting a B in the class and what is the probability of getting a B and free ice cream?

Answer 1

To get a B in the class, we need to pick balls numbered from 30-43 (both inclusive). Total favourable outcomes are 14 ( 30,31,32,33......43) and total possible outcomes are 60. Hence:-

P(getting a B)==

Favorable outcomes for getting a B and a free icecream (i.e getting even/red ball since all even are red balls too) are 30,32,34,36,38,40,42 i.e a total of 7 favorable outcomes. Hence:-

P(getting a B and free ice cream)==7/60=0.11667