Question 1134537: a die is tossed 120 times.find the probabity that face 4 will turn up
a.18 times or less
b.14 times or less
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! EDITED-- continuity correction for 19 or less is 18.5, not 17.5, which is for less than 18. For the second, use 14.5, not 13.5, which would be for less than 14. Probability of 4 is 1/6
expected value is np=(1/6)*120=20
variance is np(1-p)=20(5/6)=100/6
sd is sqrt (V)=4.08
fewer than 18 times with continuity correction uses z=(18.5-20)/4.08 or z<=-0.37
This has probability of 0.3557
14 times or less would be z<=(14.5-20)/4.08, or z<=-1.35 or probability of 0.0885
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