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Senior three math problem solving needs to be done online! !
Probability c (∮) = (3p ∮ * 9p1)/(12p (∮+1))

C(0) = 9/ 12

c( 1)= 3/ 12 * 9/ 1 1

c(2)= 3/ 12 * 2/ 1 1 * 9/ 10

c(3)= 3/ 12 * 2/ 1 1 * 1/ 10

e(∮)= 1 * c( 1)+2 * c(2)+3 * c(3)

= 0.3

Probability c (∮) = 4c ∮ * 0.4 (4-∮) * 0.6 ∮.

C(0) = 4C0 * 0.4^4

c( 1)= 4c 1 * 0.4)^3 *(0.6)

C(2) = 4C2 * 0.4^2 * (0.6)^2

C(3) = 4C3 * 0.4 * (0.6)^3

C(4) = 4C4 * 0.6^4

e(∮)= 1 * c( 1)+2 * c(2)+3 * c(3)+4 * c(4)

= 2.4