1. A company set up a kiosk in the Mall of America for several hours and asked randomly selected people which color cell phone was their favorite. The results follow:
|
White
|
10
|
|
Black
|
20
|
|
Lime
|
25
|
|
Orange
|
35
|
|
Red
|
10
|
What is the probability that a person would select orange as their favorite color?
2. Airlines monitor the causes of flights arriving late. A total of 75% of flights are late because of weather, while 35% of flights are late because of ground operations. A full 15% of flights are late because of weather and ground operations. What is the probability that a flight arrives late because of weather or ground operations?
3. A cell phone salesperson has kept records on the customers who visited his store. Forty percent of the customers who visited the store were female. Furthermore, the data show that 35% of the females who visited his store purchased a cell phone, while 20% of the males who visited his store purchased a cell phone. Let A1 represent the event that a customer is a female, A2 represent the event that a customer is a male, and B represent the event that a customer will purchase a phone.
What is the probability that a male customer will purchase a cell phone?
4. For the following probability distribution:
| x |
P(x)
|
|
10
|
.1
|
|
11
|
.25
|
|
12
|
.3
|
|
13
|
.25
|
|
14
|
.1
|
Is this a discrete distribution? Explain
The expected value is _______
The variance is _____________.
The standard deviation is ________
5. There are eight flights from Minneapolis to St. Cloud each day. The probability that any one flight is late is 0.10. Using the binomial probability formula, what is the probability that none are late?
6. A company is studying the number of daily debit card purchases. There were 20 purchases and the probability of a debit card purchase is 0.5. Would this be a binomial distribution? Explain. What is the standard deviation of the number of debit card purchases?
7. When observing a checkout line at a food store, the average number of people served is 30 per hour. Using the Poisson distribution, what is the probability that no (zero) people check out in any given hour?
8. The proportion of the area under a normal curve that is to the left of z = 1.40 is _______.
9. A sample of 500 part-time students revealed that their annual incomes were normally distributed with a mean income of $30,000 and a standard deviation of $3,000. The number of students that earned between $27,000 and $33,000 is _____.
10. What are the two parameters that determine the shape of the normal distribution? What is the mean and standard deviation in the standard normal distribution?