Males and females react differently to a circumstance. It is observed that 80% o

Question

Males and females react differently to a circumstance. It is observed that 80% of the females react positively to the circumstance, whereas only 40% of males react positively. A group of 20 people, 15 female and 5 male, was subject to these circumstances. A response picked at random from the 20 was negative. The probability that is was that of a male is: (a) 1/3, (b) 1/2, (c) 1/6, (d) 2/5. A multiple-choice question has four possible answers. The probability a student knows the answer is 3/4 and the student will guess is 1/4. The probability of guessing a correct answer is 1/4. If the student correctly answers a question, the probability that the student really knows the correct answer is: (a) 1, (b) 36/37, (c) 16/17, (d) 12/13.

Explanation / Answer

1. P(negative and female) = (15/20)x0.2 = 0.15

P(negative and male) = (5/20)x0.6 = 0.15

P( male | negative) = 0.15/(0.15+0.15) = 1/2 (option b)

2.P(guesses and correct answer) = 1/4 x 1/4 = 1/16

P(knows and correct answer) = 3/4 x 1 = 3/4

P(knows | correct answer) = (3/4)/((3/4) + (1/16)) = 12/13 (option d)

NB: Please post individual questions separately

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

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