Traditional Culture Encyclopedia - Tourist attractions - There are three scenic spots in a city: A, B and C. The probability of a guest visiting these three scenic spots is .4, .5 and .6 respectively, and which one does the guest visit?

There are three scenic spots in a city: A, B and C. The probability of a guest visiting these three scenic spots is .4, .5 and .6 respectively, and which one does the guest visit?

(1) Note that "guests visit scenic spot A",

"guests visit scenic spot B" and "guests visit scenic spot C" are A1, A2 and A3 respectively.

It is known from the conditions that A1, A2 and A3 are independent of each other,

and P(A1)=.4, P(A2)=.5. A2? .a3)+p (a1.a2a3)+p (.a1a2a3)

= .4× .5× (1-.6)+.4× (1-.5) × .6+(1-.4 )× .5× .6

. A2? A3)+P(.A1? .A2? .a3)

= .4× .5× .6+(1-.4 )× (1-.5 )× (1-.6)

= .24.

p (ξ = 1) = 1-.24 = .76. ξ ? 1 ? 3? P ? .76 ? .24 Mathematical expectation: e ξ = 1× .76+3× .24 = 1.48.