Chapter 5
What mathematical operation is used when "not" ends up in a probability problem?
Subtraction
16.9% of FBI agents are female. In a random sample of 25 FBI agents 3 are female. Identify n, p, and x.
n = 25
p = 0.169
x = 3
The time it takes a 9-year-old to eat a donut is uniformly distributed from 10 seconds to 35 seconds. What is the probability a randomly selected 9-year-old will take less than 20 seconds to eat a donut?
10/25 = 0.4
How large does a sample size need to be ensure that the central limit will apply?
At least 30
Consider a spinner that has numbers 1 to 20. What is the probability the spinner will land on a multiple of 3?
6/20
16.9% of FBI agents are female. What is the probability in a random sample of 25 FBI agents that 3 are female?
0.143
The price of college math textbooks are normally distributed with a mean of $168 and a standard deviation of $26. What is the probability a college math textbook will cost less than $125?
0.049
9.4% of children between ages 2 to 17 in the U.S. have an ADHD diagnosis. In a sample of 450 children 8% have an ADHD diagnosis.
What is the population proportion?
What is the sample proportion?
population proportion = 0.094
sample proportion 0.08
Use the contingency table in the handout... What is the probability that a randomly selected person is a student or prefers double chocolate donuts?
65/90 =0.722
You work for a bank. It is known that 3% of all credit card transactions in your region are fraudulent. You pull a sample of 75 transactions. What is the mean number of fraudulent transactions?
2.25
The price of college math textbooks are normally distributed with a mean of $168 and a standard deviation of $26. What is the probability a college math textbook will cost between $130 and $150?
0.172
9.4% of children between ages 2 to 17 in the U.S. have an ADHD diagnosis. In a sample of 450 children 8% have an ADHD diagnosis.
What is the standard deviation of the sampling distribution of proportions?
0.014
Box of 12 light bulbs. 9 are good and 3 are defective. What is the probability you randomly choose 2 and they are both good?
72/132 =0.545
You work for a bank. It is known that 3% of all credit card transactions in your region are fraudulent. You pull a sample of 75 transactions. What is the standard deviation for the number of fraudulent transactions?
1.48
The weights of adult male Labrador Retrievers are normally distributed with a mean of 87 pounds and a standard deviation of 8 pounds. What weight separates the lightest 30% of male Labrador Retrievers?
82.8 pounds
9.4% of children between ages 2 to 17 in the U.S. have an ADHD diagnosis. What is the probability in a sample of 450 children less than 8% have an ADHD diagnosis?
0.159
Use contingency table to solve this... What is the probability that a randomly selected person will be a student given they prefer glazed donuts?
16/28 = 0.571
You work for a bank. It is known that 3% of all credit card transactions in your region are fraudulent. You pull a sample of 75 transactions. Would it be unusual to find 5 fraudulent transactions? You must explain why!
No
Suppose the time that Americans spend watching TV per day is normally distributed with a mean of 2 hours and standard deviation of 0.75 hours. What time separates the longest 15% of times?
8.78 hours
The average student loan debt for college graduates is $25,050 with a standard deviation is $12,000. What is the probability a sample of 100 college graduates their mean student load debt is greater than $27,000?
0.052