Probabilistic and Statistical Techniques
HW
1
A student experiences difficulties with malfunctioning alarm clocks. Instead
of using one alarm clock, he decides to use three. What is the probability
that at least one of his alarm clocks works correctly if each individual alarm
clock has a 99% chance of working correctly?
P(at least one of his alarm clocks works correctly)= (99%)*(99%*99%)*
(99%*99%*99%)=.9
Each social security number is a sequence of nine digits. What is the
probability of randomly generating nine digits and getting your social
security number?
P(generating nine digits and getting your social security) number=(1/10)^9
2
Probabilistic and Statistical Techniques
Find the probability of getting the outcome of head and 5 when a coin is
tossed and a die is rolled
P(getting the outcome of head and 5 when a coin is tossed and a die is
rolled)
(1/6)*(1/2)=.08
A quick quiz consists of three multiple choice questions, each with five
possible answers, only one of which is correct. If you make random guesses
for each answer, what is the probability that all three of your answers are
wrong?P(all three of your answers are wrong)
(4/5)*(4/5)*(4/5)=(4/5)^3=.5
Ten percent of us are left-handed. What is the probability of randomly
selecting three people who are all left-handed?P(selecting three people
who are all left-handed) (10/100)*(9/99)*(8/98)=.27
3