1. The significance level is a point marked to compare the values of a t-test. If
the value so a t-test is higher than the significance level, then we reject the
hypothesis, and if the value of the t-test is lower than the value of the
significance level,

SDS321HW3Sol
1. How many permutations of the string of letters ABCDE are there?
5*4*3*2*1 = 5! = 120
2. How many five letter words with distinct letters are there?
26*25*24*23*22 = 7,893,600 (that is p(26,5)
3. How many five-digit numbers with distinct

Lecture 9
Random Variables
Launch: Key findings are described in news releases from AAU and UT Austin. Of note,
23.1% of female undergraduates nationwide and 18.5% at UT Austin reported being the
victim of "sexual assault by force or incapacitation" since

Lecture 6
Independence
Launch: A computer program consists of two blocks written independently, one by Alice
and the other by Bob. Alices block has an error with probability 0.2. Bobs block has an
error with probability 0.3. If the program returns an erro

Lecture 12
Common Discrete Random Variables
Launch: An internet access provider (IAP) owns two servers. Each server has a 20%
chance of being down independently of the other. Fortunately, only one server is
necessary to allow the IAP to provide service to

Lecture 7
Counting the Ways
Launch: Suppose that one node transmits on a random k out of N timeslots, the second
node listens on a random k out of N timeslots. They are both idle in the remaining N-k
timeslots. What is the probability that 2nd node hears

SDS321Lec5
Lecture 5
Bayes Theorem
Launch: A magnetic tape storing information in binary form has been corrupted, so it
can only be read with bit errors. The probability that you correctly detect a 0 is 0.8, while
the probability that you correctly detect

Lecture 14
Continuous Random variables
Launch: Suppose that the lifetime of lightbulbs made in a factory are distributed
exponentially. For one bulb, X the lifetime in years is distributed
fX(x)= 2e-2x for x0
0 otherwise
If 10 bulbs are selected, find the

SDS321HW16
Read Section Chapter 4.3, 4.5, 5.1-5.4, Start Sample Exams.
1. Let X1, X2, suppose that . be independent normal random variables with mean
0 and variance 9. Let N be a positive integer random variable with E[N] = 2 and
E[N2] = 5. We assume that