Question
A multiple choice exam is made up of 10 questions; Each question has 5 options and only one of them is correct. If a person answers at random, what is the probability of answering only 3 good questions?
115
likes574 views
Answer to a math question A multiple choice exam is made up of 10 questions; Each question has 5 options and only one of them is correct. If a person answers at random, what is the probability of answering only 3 good questions?
Hermann
4.6121 Answers
Fórmula de probabilidad binomial P(X=k)=(n,k)*p^k * (1-p)^(nk)
n=10 (10 preguntas)
k=3 (3 respuestas correctas)
p=1/5 (probabilidad de responder correctamente a una pregunta, ya que hay 5 opciones y solo una es correcta
P(X=3)=(10,3)*(1/5)^3 * (4/5)^7
P(X=3)= (10!/3!7!)(1/5)^3 * (4/5)^7 = 0,201
Entonces, la probabilidad de responder correctamente sólo 3 preguntas es aproximadamente 0,201, o 20,1%.
Frequently asked questions (FAQs)
What is the equation of an ellipse with foci at (-3,0) and (3,0), and major axis length 6 units?
+
Math question: In a right triangle, the length of one leg is 5 and the hypotenuse is 13. What is the length of the other leg?
+
What is the derivative of f(x) = x^4 + 2x^2 - 3 at x = 1?
+
New questions in Mathematics