Suppose you flip a biased coin (that lands heads with
probability p) until 2 heads appear. Let X be the number of flips
needed for this two happen. Let Y be the number of flips needed for
the first head to appear. Find a general expression for the
condition probability mass function pY |X(i|n) when n ≥ 2.
Interpret your answer, i.e., if the number of flips required for 2
heads to appear is n, what can you say about...
Flip a fair coin 100 times. Let X equal the number of heads in
the first 65 flips. Let Y equal the number of heads in the
remaining 35 flips.
(a) Find PX (x) and PY (y).
(b) In a couple of sentences, explain whether X and Y are or are
not independent?
(c) Find PX,Y (x, y).
1. A) If you flip an unfair coin 100 times, and the probability
for a coin to be heads is 0.4, then the number of heads you expect
on average is:
B) If you flip an unfair coin 100 times, and the probability for
a coin to be heads is 0.4, then the standard deviation for the
number of heads is:
C) If you flip an unfair coin 2 times, and the probability for a
coin to be heads is...
Flip a fair coin 4 times. Let ? and ? denote the number of heads
and tails correspondingly.
(a) What is the distribution of ?? What is the distribution of ?
?
(b) Find the joint PMF. Are ? and ? independent?
(c) Calculate ?(? ?) and ?(X≠?)(d) Calculate C??(?, ? ) and
C???(?, ? )
Every day you flip a fair coin four times and if it is heads all
four times, you give a dollar to charity. In a year with 365 days,
what is your expected annual donation to charity and what is the
variance?
Flip a coin 10 times. Put a 1 each time
the coin comes up heads and a 0 each time the coin comes up tails.
Count the number of heads you obtained and divide by 10. What
number did you get?
a. Is the number you obtained in part
(a) a parameter or a statistic?
b. Now flip the coin 25 times. Put a 1
each time you obtain a heads and a 0 for tails. Count the number of...
You toss a biased coin with the probability of heads as p. (a)
What is the expected number of tosses required until you obtain two
consecutive heads ? (b) Compute the value in part (a) for p = 1/2
and p = 1/4.
You flip a coin, if it is heads you will have a good day and if
it is tails you will have a bad day. There are 30 days in
total.
(a) What is the expectation and variance of the number of times
you will have a good day throughout this 30 day stretch?
(b) What is the probability that every day will be bad for all
of the 30 days?
HOMEWORK-You flip a coin FOUR times. Let H = Number of
Heads.
Calculate:
(a) P (H = 4) =
(b) P (H ≥ 1) =
(c) P (H < 4) =
(d) P (1 < H ≤ 4) =
HINT: GET YOUR SAMPLE SPACE.
Leave your answers EITHER as a simplified fraction ( e.g. 4/16 =
1/4 when simplified) OR a decimal rounded to FOUR
decimal places. Also do not forget to enter your leading zero when
entering decimals.
CAUTION: FOLLOW...