In Ms. Nelson’s homeroom classroom at Weaver High School, 18 of her 30 students

Question

In Ms. Nelson’s homeroom classroom at Weaver High School, 18 of her 30 students are taking a history class and 14 are taking a biology class.

a. If Ms. Nelson chooses a homeroom student at random, what is the probability that the student is taking a history class?

b. If Ms. Nelson chooses a homeroom student at random, what is the probability that the student is taking a biology class?

c. Explain why the sum of your answers from parts (a) and (b) is obviously not the probability that Ms. Nelson chooses a student taking a history class or a biology class.

Explanation / Answer

a) P(Student is taking a history class) = 18 / 30 = 0.6

b) P(Student is taking a biology class) = 14 / 30 = 7 / 15 = 0.4667 (Rounded off to 4 decimal places)

c) If we do the sum of part a) and part b) i.e.

P(Student is taking ahistory class) + P(Student is taking a biology class)

= 0.6 + 0.4667

= 1.0667

But the total probability can attain the maximum value of 1. Hence,

Sum of the answers from parts (a) and (b) is not the probability that Ms. Nelson chooses a student taking a history class or a biology class. There would be some students who are taking both the classes.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.