A game is played by rolling a six sided die which has four red faces and two blue faces. One turn consists of throwing the die repeatedly until a blue face is on top or the die has been thrown 4 times
Adnan and Beryl each have one turn. Find the probability that Adnan throws the die more turns than Beryl
I tried :
Adnan throws two times and Beryl throws once = 23 x 13
Adnan throws three times and Beryl throws once =49 x 13
Adnan throws three times and Beryl throws twice = 49 x 23
Adnan throws four times and Beryl throws once = 827 x 13
Adnan throws four times and Beryl throws twice = 827 x 23
Adnan throws four times and Beryl throws three times =827 x49
The answer says 0.365
Please help
Answer
When Beryl throws the die once, Adnan can throw it 2,3 or 4 times. The required probability is13⏟Beryl=1(1−13⏟Adnan=1)Similarly, when Beryl throws the die 2 times, Adnan may throw 3 or 4 times, giving the required probability2313⏟Beryl=2(1−(13⏟Adnan=1+2313⏟Adnan=2))and when Beryl throws it 3 times, Adnan throws the die 4 times. The last throw could result in a red face or a blue face. So the probability of this case is232313⏟Beryl=3(232323[23+13]⏟Adnan=4)The sum of these terms yields the required answer.
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