in a room filled with 7 people , 4 people have exactly 1 sibling in the room and 3 people have exactly 3 siblings in the room . if two individuals are selected from the room at random , what is the probability that those two individuals are not siblings ?
"there are suppose a b c d e f g members in the room 4 people who have exactly one sibling . . . . a b c d . . . . ( a is bs ∘ sssibl ∈ g ∘ ssand ∘ ssviceversa ) ∘ ss ( c ∘ ssis ∘ ssds ∘ sssibl ∈ g ∘ ssand ∘ ssviceversa ) ∘ ss ( c ∘ ssis ∘ ssdssibl ∈ gandviceversa ) ( cisds sibling and viceversa ) ( c is ds sibling and viceversa ) . . . now remaning efg are 3 people who have exactly 3 siblings . . . . ( e has f and g as his / her sibling and so on . . ) there are now 3 different set of siblings ( a and b ) ( c and d ) ; ( efg ) now first selecting 3 people out of 7 is 7 c 3 = 35 first sibling pair - - - - ( a and b ) - - selecting 3 people - - 3 c 3 = 1 second sibling pair ( c and d ) - - selecting 3 people - - 3 c 3 = 1 third sibling pair ( e f g ) - - selecting 3 out of 3 - - 3 c 3 = 1 total = 1 + 1 + 1 = 3 but , a / c to formula p ( success ) - 1 - p ( fail ) here , p ( failure ) is selecting 3 people who are siblings = 3 / 35 ( 35 is 7 c 3 ) = 1 - 3 / 35 = 32 / 35 ans e"
add(multiply(divide(4, 7), divide(subtract(7, 3), subtract(7, 1))), multiply(divide(4, 7), divide(subtract(7, 4), subtract(7, 1))))