IFY-Maths-2-Business-Probability相关知识学习.ppt

W T T/ W W/ W/ (ii) (ii) W T T/ W W/ W/ (ii) W T T/ W W/ W/ We can deduce an important result from the conditional law of probability: ( The probability of A does not depend on B. ) or P(A and B) = P(A) ? P(B) If B has no effect on A, then, P(A B) = P(A) and we say the events are independent. becomes P(A) = P(A and B) P(B) So, P(A B) = P(A and B) P(B) SUMMARY For 2 independent events, P(A and B) = P(A) ? P(B) P(A B) = P(A) So, e.g. 2. I have 2 packets of seeds. One contains 20 seeds and although they look the same, 8 will give red flowers and 12 blue. The 2nd packet has 25 seeds of which 15 will be red and 10 blue. Draw a Venn diagram and use it to illustrate the conditional probability formula. Solution: R F 15 8 12 Blue in the 2nd packet Let R be the event “ Red flower ” and F be the event “ First packet ” e.g. 2. I have 2 packets of seeds. One contains 20 seeds and although they look the same, 8 will give red flowers and 12 blue. The 2nd packet has 25 seeds of which 15 will be red and 10 blue. Draw a Venn diagram and use it to illustrate the conditional probability formula. Solution: R F 15 10 8 12 Blue in the 2nd packet Let R be the event “ Red flower ” and F be the event “ First packet ” e.g. 2. I have 2 packets of seeds. One contains 20 seeds and although they look the same, 8 will give red flowers and 12 blue. The 2nd packet has 25 seeds of which 15 will be red and 10 blue. Draw a Venn diagram and use it to illustrate the conditional probability formula. Solution: R F 15 10 8 12 Total: 20 + 25 Let R be the event “ Red flower ” and F be the event “ First packet ” 45 e.g. 2. I have 2 packets of seeds. One contains 20 seeds and although they look the same, 8 will give red flowers and 12 blue. The 2nd packet has 25 seeds of which 15 will be red and 10 blue. Draw a Venn diagram and use it to illustrate the conditional probability formula. Solution: R F 15 10 8 12 Total: 20 + 25 Let R be the event “ Red flower ” and F be the event “ Fi