Probability

CFA Level I
#1

A discount brokerage firm states that the time between a customer order for a trade and the execution of the order is uniformly distributed between three minutes and fifteen minutes. If a customer orders a trade at 11:54 A.M., what is the probability that the order is executed after noon? A) 0.750. B) 0.500. C) 0.125. D) 0.250. Can someone pls show me how to calculate this probability

#2

The range is 3 - 15 minutes (a difference of 12 minutes) and the odds of it being executed in less than 6 minutes (12:00PM minus 11:54AM) is 3/12 or .250 so the odds of it being more is .750. i think… Is it A?

#3

question asks AFTER noon so 6/12 0.5 Choice B?

#4

it does say afternoon, but the first possible time is 3 minutes later so i agree with broken the last time a trade can be executed is 1209 so 9 times are afternoon or 9/12 = 75%

#5

A: (12-3)/12=0.75

#6

12- 11.54/15-3=.5 answer is B

#7

but the first trade can’t happen at 1154, it can only happen at 1157, as it says it takes at least 3 minutes to do a trade and can take 15 minutes

#8

Answer is B. Go with CP and ssndola

#9

Between 3 and 15 minutes @@ To me there is no answer. 15-3 +1 = 13 Each probabiliby is 1/13 After NOON = from 7 minutes onwards = 9/13. No?

#10

In my opinion 0.75 is the right answer. The earliest time the order can be executed is 11.57 the latest is 12.09 so the range is 12 minutes and only 9 minutes satisfy the condition that the delivery is in the afternoon. 9/12 =0.75 so answer A is correct!!

#11

Those of you that are choosing B are forgetting to add the 3 minute delay it takes to process the order onto 11:54. Taking the 3 minute delay into consideration makes the correct answer A.

#12

I vote for A. t is uniformly distributed between [3,15]. the probability of t being greater than 6 is (15-6)/(15-3) = 0.75

#13

I vote b. t is uniformly distributed (3,15). uniform distribution = 1/[15-3] =1/12. probability of it being at 11:57 = 3/12 = .20 probability of it being at 1200 =6/12 = .50

#14

Correct Answer is A. I realized my mistake: For continuous dist: CDF = X-A/B-A = 6-3/15-3 = .25 (This gives us probability of X being less than or equal to 6) So probability of X > 6 is 1 - .25 = .75…