In statistical survey of 1003 families of Kolkata, it was found that 63 families has neither a radio nor a TV 794 families has a radio and I87 has TV. The number of families in that group having both a radio and a TV is

Let R be the set of families having a radio and Z be the set of families having a TV.Then,n(R∪T)= Number of families having at least one of the radio and TV= 1003 - 63 = 940n(R)=794 and n(T)=187Let x be the number of families having both a radio and a TV.Then number of families who have only Radio = 794 - xNumber of families who have only TV = 187 - xFrom Venn diagram,794−x+x+187−x=940⇒ 981−x=940∴ x=981−940=41Hence, the required number of families having both a radio and a TV is 41.