manOnFire wrote:
bmwhype2 wrote:
1.
Prob that Sally will not win = 4/5
Prob that Jeny will not win = 4/5
Hence 4/5 * 4/5 = 16/25
correct?
Can someone explain the flaw here?
5 women are in a race.
What is the probability that Sally and Jenny both will not win the race?
Say S,J, X1,X2,X5 are in the race.. [ assuming the only one person will win the race out of 5 with equal probablity]
All these events[Winning S, Winning J, Winning X1.] are "mutually exclusive" --> Out comes are not common.
P(S) = 1/5
P(J) =1/5
P(X1)=1/5
P(X2)=1/5
P(X3)=1/5
probability of either one of them winning hte race
= P(S or J or X1 or X2 or X3) =P(S) +P(J)+P(X1)+P(X2)+P(X3) =1
probability that Sally and Jenny both will not win the race = probability that either one of X1 or X2 or X2 them win the race = P(X1)+P(X2)+P(X3) =1/5+1/5+1/5=3/5
check the below link, it may be useful for you.
http://www.regentsprep.org/regents/math/mutual/Lmutual.htm