A wheel contains eight slices, numbered sequentially 1 through 8 The probability of landing on each slice is equal. The wheel is spun two times. What is the probability that the sum of the two spins is greater than 10?

1 Answer
MeneerNask
Jul 4, 2017

There are #64# possible outcomes, from #1+1to8+8#

Explanation:

The favourable ones are the ones that add up to #>=11#

These are:
#38,47,48,56,57,58,65,66,67,68,74,75,76,77,78,83,84,85,86,87,88# for a total of #21#
(if you put this in a matrix with first spin as columns and second spin as rows it will be easier to see and count)

#->P(>10)=P(>=11)=21/64# or just under a third.

Or:
For a first spin of #1or2# there is no possible favourable outcome.
First spin #3->1# possible favourable outcome #(3+8#)
First spin #4->2#, first spin #5->3#, etc.
Then add #1+2+3+4+5+6=21#

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