MATH 166 Topics in Contemporary Math II
Joseph Noles
Spring 2015
Instructor:
Quiz 9
All answers must be left in terms of the combination and permuation functions C(n,k)
and P(n,k). Do not use a calculator or computer to calculate the answers.
Exercise 1. (0 points) Print your name at the top right corner of the back of this
paper.
Exercise 2. (5 points) A coin is weighted so that the probability of heads is 0.7. This
coin is flipped 10 times.
a) What is the probability of getting heads exactly 8 times?
b) What is the probability of getting heads at least 7 times, but no more than 9 times?
c) What is the expected number of times you get heads?
Exercise 3. (5 points) A bag contains 9 spherical objects, 1 red, 3 white and 5 blue.
The objects are randomly drawn from the bag without replacement until a white object
is drawn. Let X be the random variable counting the number of objects drawn from
the bag.
c
Joseph
Noles, March 3, 2015.
1
a) Is X a finite, infinite discrete or countinuous random variable?
b) Calculate P (X ≤ 2).
c
Joseph
Noles, March 3, 2015.
2