Distributions flashcards
32 practice cards drawn from the Distributions lessons. Tap a card to turn it over. Every answer is checked against the lesson it came from.
Read the Distributions lessons in full →
Is the time a bus takes to arrive discrete or continuous?
continuous
from “Random Variables”
Is the number of heads in 10 tosses discrete or continuous?
discrete
from “Random Variables”
Outcomes A, B and C have probabilities , and . What is D?
from “Probability Distributions”
Outcomes A, B and C have probabilities , and . What is D?
from “Probability Distributions”
X is 0 with probability and 14 with probability . What is E(X)?
7
from “Expected Value”
X is 0 with probability and 6 with probability . What is E(X)?
3
from “Expected Value”
X is 7 or 15, each with probability . What is Var(X)?
16
from “Variance”
X is 5 or 11, each with probability . What is Var(X)?
9
from “Variance”
E(X) = 3. What is E(3X + 5)?
14
from “Transforming a Random Variable”
Var(X) = 6. What is Var(2X + 9)?
24
from “Transforming a Random Variable”
Are these Bernoulli trials: rolling a die 10 times and counting sixes?
yes
from “Bernoulli Trials”
Are these Bernoulli trials: tossing the same coin 20 times?
yes
from “Bernoulli Trials”
X ~ . What is P(X = 2)?
from “The Binomial Distribution”
In how many ways can exactly 2 of 5 trials succeed?
10
from “The Binomial Distribution”
X ~ . What is the mean?
6
from “Binomial Mean and Variance”
X ~ . What is the mean?
7
from “Binomial Mean and Variance”
Can a binomial model be used if the sample is drawn without replacement from a small group?
no
from “Modeling with a Binomial”
Can a binomial model be used if p changes partway through?
no
from “Modeling with a Binomial”
For a continuous variable, what is P(X = 4) exactly?
0
from “Continuous Variables”
For a continuous variable, what is P(X = 2) exactly?
0
from “Continuous Variables”
Roughly what percent lies within 3 standard deviations of the mean?
99.7%
from “The Normal Distribution”
Roughly what percent lies within 1 standard deviation of the mean?
68%
from “The Normal Distribution”
The mean is 35 and sigma is 10. What is the z-score of 55?
2
from “Standardizing”
The mean is 54 and sigma is 10. What is the z-score of 34?
-2
from “Standardizing”
The area to the left of z is 0.9750. What is z?
1.96
from “Reading the Z-Table”
You want 1 percent in the upper tail. Which area do you look up?
0.9900
from “Reading the Z-Table”
What is P(2.33 < Z < 2.58)?
0.0050
from “Reading Normal Probabilities”
What is P(1.645 < Z < 1.96)?
0.0250
from “Reading Normal Probabilities”
The mean is 41 and sigma is 5. Which value has z = 2?
51
from “Inverse Normal”
The mean is 25 and sigma is 2. Which value has z = -2?
21
from “Inverse Normal”
X and Y are independent with Var(X) = 6 and Var(Y) = 4. What is Var(X − Y)?
10
from “Combining Normals”
X and Y are independent with Var(X) = 8 and Var(Y) = 7. What is Var(X − Y)?
15
from “Combining Normals”