SOLUTION: the chances that a student passes the promotional examination at the first sitting in physics, biology and chemistry are respectively 0.4,0.5 and 0.1. what is the probability tha

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Question 1074027: the chances that a student passes the promotional examination at the first sitting in physics, biology and chemistry are respectively 0.4,0.5 and 0.1. what is the probability that the student fails
a) only one subject
b) at least one subject
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Look at the possible outcomes for failing one subject.
FPP, PFP, PPF
So,

P%28X=1%29=0.03%2B+0.02+%2B+0.18
P%28X=1%29=0.23
.
.
Let's look at the one outcome where the student fails no subjects first.
P%28X=0%29=%280.4%29%280.5%29%280.1%29
P%28X=0%29=0.02
So then the complement encompasses failing at least one subject.
P%28X%3E=1%29=1-0.02
P%28X%3E=1%29=0.98