Addition Rule
Amanda spins a spinner numbered 1 to 10. What is the probability that the spinner lands on an odd number or a number that is divisible by 3?
(5/10) + (3/10) - (2/10) = 3/5 or 60%
True or False?
If two events are independent, then P(A|B) = P(B).
False! They are dependent of each other.
Anna has a bag of marbles for her little sister. It contains 12 red marbles, 6 white marbles, and 2 blue marbles. She drops the bag and three marbles roll out. What is the probability that all 3 marbles are white?
(6/20)*(5/19)*(4/18) = 1/57
If we want to calculate the probability of rolling a 6 for the first time on the 6th roll of a die, would we use the geometric or the binomial distribution?
geometric
Where did Ms. V go to college?
St. John Fisher College
A group of 5 men and 5 women are applying for two job positions. Each of the 10 job candidates has the same chance of receiving a job offer. What is the probability that the company will hire a man or a woman for each of the two positions?
1
Mary is a good student. The probability that she studies and passes her test is 3/5. The probability that she studies is 8/9. What is the probability that she passes given that she studies?
(3/5)/(8/9) = 27/40 or 67.5%
A bag contains 5 red marbles, 4 blue marbles, and 3 green marbles. Joshua will select a marble at random, record its color, and then put the marble back in the bag. He will select three marbles in this way. What is the probability that Joshua will first get a red marble, then a blue marble, and then a green marble?
(5/12)*(4/12)*(3/12) = 5/144
When rolling a fair die 100 times, what is the probability of rolling a "4" exactly 25 times? Is this an example of binomial or geometric?
Binomial
Which month is Ms. V's birthday in?
May
A seven-sided number cube with sides numbered 1, 2, 3, 4, 5, 6, 7 is rolled. What is the probability that a 4 or an odd number is rolled?
1/7 + 4/7 = 5/7
A new credit card has been issued to 2000 customers. Of these customers, 1500 hold a visa, 500 hold an AA card, and 40 hold a Visa AND AA card. Find the probability that a randomly chosen customer holds an AA, given they hold a Visa.
40/1500 = 0.0267
John has seven keys on a ring. He gives these keys to his friend Robin and asks her to unlock a door. If two of the seven keys can unlock the door, what is the probability that Robin unlocks the door on exactly her third attempt?
(5/7)*(5/7)*(2/7) = 40/210
The American Red Cross says that about 11% of the U.S. population has Type B blood. A blood drive is being held at your school. What is the probability that exactly 2 of the first 20 blood donors have Type B blood?
binompdf(20, 0.11, 2) = 0.282
Name a tv show that I usually watch...
Grey's Anatomy, Big Brother, The Bachelor/Bachelorette/Bachelor in Paradise, etc.
A box contains 18 blue flashlights, 3 red flashlights, 7 silver flashlights, and 2 black flashlights. The flashlights are identical in size and shape. If one flashlight is chosen at random, what is the probability that the flashlight will be either blue or black?
18/30 + 2/30 = 2/3
45% total of the children in a school have a dog, 30% total have a cat, and 18% have a dog and a cat. What percent of those who have a cat given they had a dog first?
18%/45% = .40%
Carlos has a spinner that is divided into 3 equal-sized sectors numbered from 1 to 3, and a number cube labeled from 1 to 6. He will spin the arrow of the spinner and roll the number cube one time. What is the probability that the arrow will land on a sector labeled 3, and the number cube will land on a number less than 3?
(1/3)*(2/6) = 1/9
The owner of a pet store is trying to decide whether to discontinue selling specialty clothes for pets. She suspects that only 4% of the customers buy specialty clothes for their pets. What is the probability that she does NOT sell a garment until the 7th customer? Assume each customer is independent.
geompdf(0.04,7) = 0.0313
Where is my hometown?
Henrietta, NY
A total of 540 customers, who frequented an ice cream shop, responded to a survey asking if they preferred chocolate or vanilla ice cream. 308 of the customers preferred chocolate. 263 of the customers were female. 152 of the customers were males who preferred vanilla ice cream.
What is the probability that a customer chosen at random is a male or prefers vanilla ice cream?
(277/540) + (232/540) - (152/540) = 119/180 or 66.11%
A jar contains black and white marbles. Two marbles are chosen without replacement. The probability of selecting a black marble and then a white marble is 0.34, and the probability of selecting a black marble on the first draw is 0.47. What is the probability of selecting a white marble on the second draw, given that the first marble drawn was black?
0.34/0.47 = 72.3%
There are 9 movies showing at a theater. Two are action movies, two are children’s movies, and the other movies are comedies. Ashley randomly selects 2 different movies to see. What is the probability that the first movie is an action movie and the second movie is a comedy?
(2/9)*(5/8)=5/36
A manufacturer of metal pistons finds that on average, 12% of his pistons are rejected because they are either oversize or undersized. What is the probability that a batch of 10 pistons will contain at least 2 rejects?
1 - binomcdf(10, 0.12, 2) = 0.34173
What is my favorite musical?
Rent