box A has place for 2 balls,(adsbygoogle = window.adsbygoogle || []).push({});

box B has place for 3 balls

balls are placed randomly in each of the boxes until one of them is full

if X is the amount of balls used, find:

E(x)

var(x)

i drew the boxes and think there are only 3 options,,, X=[2 3 4]

BOX A --- BOX B

I) 2 balls ---- 0 balls

II) 2 balls --- 1 ball

III) 2 balls --- 2 balls

IV) 1 ball --- 3 balls

V) 0 balls --- 3 balls

|__X || 2__|_3__|_4_|

|P(X) || 1/5 | 2/5 | 2/5|

E(X)=3.2

but the correct answer is 3.125

same problem (obviously) for var

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# Homework Help: Probability - Drawing balls from boxes

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