anairamitch1804 wrote:
Since the first two digits of the license plate are known and there are 10 possibilities for each of the remaining two digits (each can be any digit from 0 to 9), the total number of combinations for digits on the license plate will equal 10 ×10 = 100.
Because there are only 3 letters that can be used for government license plates (A, B, or C), there are a total of nine two-letter combinations that could be on the license plate (3 possibilities for first letter × 3 possibilities for the second letter).
Given that we have 100 possible digit combinations and 9 possible letter combinations, the total number of vehicles to be inspected will equal 100 × 9 = 900.
Since it takes 10 minutes to inspect one vehicle, the police will have time to inspect 18 vehicles in three hours (3 hours = 180 minutes). Thus, the probability of locating the transmitter within the allotted time is 18/900 = 1/50. The correct answer is D.
Hi, this question really gave me some problems,but I could finally do it. My question from you is derived from the following that you have written:-
Since it takes 10 minutes to inspect one vehicle, the police will have time to inspect 18 vehicles in three hours (3 hours = 180 minutes). Thus, the probability of locating the transmitter within the allotted time is 18/900 = 1/50.I agree that in 3 hours, the number of vehicles that can be tested is 18, and we have 900 vehicles in total that may be tested.
What we have to find, is the probability that we find our transmitter vehicle in no more than 18 attempts. That would translate into - the first vehicle is our vehicle or the first is some other vehicle and then our vehicle or .....
What you have done is simply divided
The cars we can check by
The total number of cars that are there.
I cannot understand the connection, how does this give us the answer?
Bunuel VeritasPrepKarishma please help. I am trying to actually fully understand the concepts of probability, this would really help fetch a higher score. Thanks a lot