IBDP Mathematics Question Analysis Topic: Mathematics - Probability
Exam Question:
Of the students in a school, it is known that 30% have 100% attendance and 70% students are irregular. Previous year results report that 70% of all students who have 100% attendance attain A grade and 10% irregular students attain A grade in their annual examination. At the end of the year, one student is chosen at random from the school and he was found to have an A grade. What is the probability that the student has 100% attendance? Is regularity required only in school? Justify your answer.
Answer:
For IBDP Mathematics, you should know:
If 70% of students are irregular and 30% are in full attendance, then let a = 0.3 be the chance of full attendance.
Let b = 0.7 be the chance of irregular attendance.
Given that 10 percent of students with irregular attendance earn grades of A, and also 70% of students with 100% attendance do:
The odds of a pupil being picked up with an A are 0.7 x 0.3 + 0.7 x 0.1 = 0.21 + 0.07 = 0.28.
The chosen student's likelihood of having perfect attendance will be 0.21/0.28 = 3/4.
No, regularity is necessary in all facets of our lives.
Work hard for your IBDP Mathematics examination!
End of analysis. Great!