A survey is conducted to find out whether people in metropolitan areas obtain their news from television (Event T), an newspaper (Event N), or radio (Event R). The results show that 70% of people get news on television, 62% from newspapers, 46% from radio, 42% from television and newspapers, 26% from television and radio, 18% from newspapers and ratio, and 3% from television, newspapers and radio. e) Given that TV is a news source, what is the probability that radio is not a news source?f) Given that newspaper is a news source, what is the probability that TV is not a news source?g) Given that newspaper is a news source, what is the probability that radio is not a news source?h) Given that both newspaper and radio are news sources, what is the probability that TV is not a news source?

e) P ( R' | T ) = 0.62857

f)  P ( T' | N ) = 0.32258

g)  P ( R' | N ) = 0.70968

h) P ( T' | N&R ) = 5/6

Step-by-step explanation:

Given:

- The probability of Television as news source P ( T ) = 0.7

- The probability of Newspaper as news source P ( N ) = 0.62

- The probability of Radio as news source P ( R ) = 0.46

- The probability of Television & Newspaper as news source P (T&N) = 0.42

- The probability of Television & Radio as news source P (T&R) = 0.26

- The probability of Radio & Newspaper as news source P (R&N) = 0.18

- The probability of all 3 as news source P ( T & R & N ) = 0.03

Find:

Given that TV is a news source, what is the probability that radio is not a news source?

Given that newspaper is a news source, what is the probability that TV is not a news source?

Given that newspaper is a news source, what is the probability that radio is not a news source?

Given that both newspaper and radio are news sources, what is the probability that TV is not a news source?

Solution:

- We will first compute the individual probability of each event occurring alone.

   P (Television is the only news source) = P(T) - P(T&R) - P(T&N) + P(T&N&R)

   P ( Only Television ) = P ( only T ) = 0.7 - 0.42 - 0.26 + 0.03 = 0.05

   P (Newspaper is the only news source) = P(N)-P(N&R)-P(T&N)+P(T&N&R)

   P ( Only Newspaper ) = P ( only N ) = 0.62 - 0.18 - 0.42 + 0.03 = 0.05

   P (Radio is the only news source) = P(R) - P(T&R) - P(N&R) + P(T&N&R)

   P ( Only Radio ) = P ( only R ) = 0.46 - 0.26 - 0.18 + 0.03 = 0.05

- Now for part e)

   We are asked for a conditional probability of the form as follows:

            P ( R' | T ) = P ( R' & T ) / P ( T )

   First compute the probability that next news source is not Radio provided it is already a source of TV.                              

            P ( R' & T ) =  P( only T ) + P ( only T & N ) = 0.05 + 0.42 - 0.03 = 0.44

Hence,

            P ( R' | T ) = 0.44 / 0.7

            P ( R' | T ) = 0.62857

- Now for part f)

   We are asked for a conditional probability of the form as follows:

            P ( T' | N ) = P ( T' & N ) / P ( N )

   First compute the probability that next news source is not TV provided it is already a source of Newspaper.                              

            P ( T' & N ) =  P( only N ) + P ( only R & N ) = 0.05 + 0.18 - 0.03 = 0.2

Hence,

           P ( T' | N ) = 0.2 / 0.62

           P ( T' | N ) = 0.32258

- Now for part g)

   We are asked for a conditional probability of the form as follows:

            P ( R' | N ) = P ( R' & N ) / P ( N )

   First compute the probability that next news source is not Radio provided it is already a source of Newspaper.                              

            P ( R' & N ) =  P( only N ) + P ( only T & N ) = 0.05 + 0.42 - 0.03 = 0.44

Hence,

            P ( R' | N ) = 0.44 / 0.62

            P ( R' | N ) = 0.70968

- Now for part h)

   We are asked for a conditional probability of the form as follows:

            P ( T' | N&R ) = P ( T' & N & R) / P ( N & R )

   First compute the probability that next news source is not TV provided it is already a source of both radio and Newspaper.                              

            P ( T' & N & R) = P ( only N & R ) = 0.18 - 0.03 = 0.15

Hence,

            P ( T' | N&R ) = 0.15 / 0.18

            P ( T' | N&R ) = 5/6