Expected Payouts
In July in Seattle, the grass grows 1⁄2 in. a day on a sunny day and 1⁄4 in. a day on a cloudy day. In Seattle in July, 75% of the days are sunny and 25% are cloudy. Find the expected amount of grass growth on a typical day in July in Seattle.
0.75(0.5) + 0.25(0.25) = 0.4375 inches
If a die is rolled one time, find the probability of getting a number greater than 3 or an odd number
What is 5/6 or .8333
If 25% of US federal prison inmates are not US citizens, find the probability that 2 randomly selected federal prison inmates will not be US citizens
What is .063
At the Scituate Art Festival, the likelihood that a person visits the pottery tent and purchases an item is 28%. What is the probability that the eighth person to visit the pottery tent is the first to buy a piece?
.0281
A math teacher gave her class two tests. 25% of the class passed both tests and 42% of the class passed the first test. What percent of those who passed the first test also passed the second test?
0.60 = 60%
The Wilmington Investment club is considering purchasing a certain stock. After considerable research, the club members determine that there is a 60% chance of making $8000, a 10% chance of breaking even and a 30% chance of losing $6200. Find the expected value of this purchase.
0.6(8,000) + .3(-6,200) = $2940
If one card is drawn from a deck of cards, find the probability of getting a 6 or a spade
What is 4/13 or .3077
The Gallup Poll reported that 52% of Americans used a seat belt the last time they got into a car. If 4 people are selected at random, find the probability that they all used their seat belt the last time they got into a car.
What is .073
The probability that a randomly chosen individual has an automobile accident in a given year is 18%. Find the probability that exact 3 out of 20 driving adults have an accident in a given year?
.2278
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?
What is .72 or 72%
You pay $10 to play the following game of chance. There is a bag containing 12 balls, five are red, three are green, and the rest are yellow. You are to draw one ball from the bag.
You will win $14 if you draw a red ball and you will win $12 if you draw a yellow ball.
How much do you expect to win or lose if you play this game once?
-0.167
A couple has two children. Find the probability that they have 2 boys.
.25
If 28% of US medical degrees are conferred to women, find the probability that 3 randomly selected medical schools graduates are men.
What is 0.373
The probability that a randomly chosen individual has an automobile accident in a given year is 18%. Find the probability that 3 or fewer out of 20 driving adults have an accident in a given year?
.5026
The probability that it is Friday and that a student is absent is 0.03. Since there are 5 school days in a week, the probability that it is Friday is 0.2. What is the probability that a student is absent given that today is Friday?
.15 or 15%
At Raleigh Raceway, your horse, Slow Rider, has a probability of 1/20 of coming in first place, a probability of 1/10 of coming in second place, and a probability of 1⁄4 of coming in third place. First place pays $4,500 to the winner, second place $3,500, and third place $1,500. Is it worthwhile to enter the race if it costs $1,000?
(1/20)(3500) + (2/20)(2500) + (5/20)(500) + (12/20)(-1000) = -$50. Do not enter the race.
At a convention there are 7 math teachers, 5 computer science teachers, 3 statistics teachers and 7 science teachers. If an instructor is selected at random, find the probability that a science or statistics teachers is chosen.
What is 5/11 or .4545
A flashlight has 6 batteries, 2 of which are defective. If 2 are chosen at random without replacement, find the probability that both are defective.
What is 1/15 or .0667
Type A blood is found in 43% of the population. What is the probability that it will take 3 or fewer people before you find a person with Type A blood?
.814807
At Kennedy Middle School, the probability that a student takes Technology and Spanish is 0.087. The probability that a student takes Technology is 0.68. What is the probability that a student takes Spanish given that the student is taking Technology?
.13 or 13%
At an outdoor flea market, the organizer estimates that 2000 people will attend if it does not rain and 700 people will attend if it does rain. The weather forecast indicates that there is a 60% chance of rain on the day of the seminar. Determine the expected number of people who will attend the flea market.
2000(0.4) + 700(0.6) = 1220 is the expected number of people
At a particular school with 200 male students 58 play football, 40 play basketball, and 8 play both. What is the probability that a randomly selected male student plays neither sport?
What is 0.55
What is probability of picking an ace from a deck of cards, then picking a spade and then picking another ace. WITHOUT REPLACEMENT
What is .719
Type A blood is found in 43% of the population. What is the probability that it will take more than 3 people before you find a person with Type A blood?
1-geometcdf(.43,3)
= .185193
In New York State, 48% of all teenagers own a skateboard and 39% of all teenagers own a skateboard and roller blades. What is the probability that a teenager owns roller blades given that the teenager owns a skateboard?
What is .81 or 81%