exponential decay word problem

[goldcantstay]

Suppose you have 30 dice, roll the dice continuously and remove a die if a 6 lands face up.
a) Write an equation to model the number of dice remaining after each toss.
b) Write an equation to model the number of dice remaining after each toss if you remove a die if either a 1 or a 6 is face up.

Not sure what to do because there's no way to tell how many sixes there will be.

 

[tkhunny]

Not sure what to do because there's no way to tell how many sixes there will be.

It's called a distribution.

Pr(30 sixes) = (1/6)^30
Pr(29 sixes) = 30*(1/6)^29*(5/6)
and so on.