A Question From Probability

Topic : Probability Word Problem

Question : In transmitting dot and dash signals, a communication system changes ¼ of the dots to dashes and 1/3 of the dashes to dots. If 40% of the signals transmitted are dots and 60% are dashes, what is the probability that a dot received was actually a transmitted dot?

Solution :
[a]Dot Signals transmitted = 40%
[b]Dash signals transmitted = 60%
Let A be the event of receiving a dot.
And B the event of a transmitted dot received as dot.
So the required probability P(BA). = P(A and B)/P(A).
P(A) = 3/4 X 0.40 + 1/3 X 0.60 = 0.30 + 0.20 = 0.50
P(A and B) = 3/4 X 0.40 = 0.30
So the required Probability = P(BA) = 0.30/0.50 = 3/5.

Differences between Theoretical Probability and Experimental Probability

Topic : Theoretical Probability and Experimental Probability

Question : "Theoretical Probability" and the differences between "Theoretical Probability and Experimental Probability"

Answer :
Theoretical probability is the chance of an event happening as determined by calculating the mathematical result.
Experimental probability is the chance of an event happening based in repeated testing or observation
For example, if I flip a coin the theoretical probability of a Heads is 1 / 2
whereas the experimental probability is often quite different.
When the number of experiments increase(quite a big number) the experimental probability in the absence of any other bias tends to match the theoretical probability.

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