## anonymous one year ago I WILL GIVE MEDAL/FAN The probability that a train leaves on time is 0.9. The probability that the train arrives on time and leaves on time is 0.36. What is the probability that the train arrives on time, given that it leaves on time? 0.6 0.9 0.27 0.36

1. anonymous

@Michele_Laino @ganeshie8 @dan815 @pooja195

2. anonymous

@hartnn

3. hartnn

Use the normal conditional probability formula \(\Large P(A/B) = \dfrac{P(A \cap B )}{P(B)}\) A here is event that the train arrives on time. B is the event that the train leaves on time.

4. anonymous

What do I put for the variables?

5. hartnn

P(B) = probability that the train leaves on time = 0.9 P(A \(\cap \)B) = probability that the train leaves on time and arrives on time = 0.36

6. hartnn

are you sure those options/choices are correct? can you please post the screenshot of the question and options?

7. anonymous

P(A∩B) .39 P(A/B)= ----- = --- = .4 is not an answer P(B) .9

8. anonymous

Yes ok

9. anonymous

10. hartnn

yes, 0.4 is the correct answer. none of the choices have 0.4, there could be the mistake while giving choices. In that case,I would select the nearest option 0.36, if i have to select one..

11. anonymous

Okay thank you! Can you help me with another question?

12. anonymous

Chocolate Chippers wants to see if their new chocolate bar is enjoyed more by high school or middle school students. They decide to visit one middle school and one high school in Atlanta, GA. After interviewing 75 students at each school, they determine that middle school students like their chocolate more than the high school students do. What is the sample of the population? All students who attend middle school or high school in the country All students who attend middle school or high school in Atlanta, GA All students who attend one middle school and one high school in Atlanta, GA All students who attend middle school or high school in Georgia

13. hartnn

"They decide to visit one middle school and one high school in Atlanta, GA." this statement gives us the sample space. so, now what do you think is the answer?

14. anonymous

c? All students who attend one middle school and one high school in Atlanta, GA

15. hartnn

thats right :)

16. anonymous

Thank you!

17. anonymous

Can you help me with this one: A doctor wants to know if her patients are happy with her. She decides to survey a sample of her clients. What method would be best for choosing a random sample that is a fair representation of her patients? Assign numbers to each patient and then use a random number generator to choose one hundred patients to survey. Give a survey to the next one hundred patients who come to the office. Call the first one hundred patients in alphabetical order. Ask the nurse to refer one hundred patients to call.

18. hartnn

random number generator will give the most fair random sample.

19. anonymous

What does that mean?

20. hartnn

It means that we should use random number generator when we want a fair random sample. A random number generator will select a random number from a number space without any bias. so the doctor should assign numbers to each patient and then use a random number generator to choose one hundred patients to survey.

21. anonymous

Oh thanks !!!

22. hartnn

welcome ^_^