Unit Test — Unit test Answers

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6

The owner of a local movie theater keeps track of the number of tickets sold in each purchase and makes a probability distribution based on these records. Let X represent the number of tickets bought in one purchase. The distribution for X is given in the table.

Question illustration
A
The number of tickets purchased typically varies from the expected value by 0.95 tickets.
B
If many, many purchases are made, the expected number of tickets purchased is 2.1.
C
The mean number of tickets purchased typically varies from the expected value by 0.95 tickets.
D
The mean number of tickets purchased typically varies from the expected value by 0.89 tickets.
9

There are 16 students in a science class. Let X represent the number of students born on a Tuesday. Assuming birthdays in this class are independent of one another, what are the mean and standard deviation of X?

A
Mu Subscript x Baseline = 2.29, Sigma Subscript x Baseline = 1.40
Option A
B
Mu Subscript x Baseline = 3, Sigma Subscript x Baseline = 1.96
Option B
C
Mu Subscript x Baseline = 7, Sigma Subscript x Baseline = 1.51
Option C
D
Mu Subscript x Baseline = 13.71, Sigma Subscript x Baseline = 3.84
Option D
10

Two students have devised a dice game named “Sums” for their statistics class. The game consists of choosing to play odds or evens. Probabilities for “Sums”Roll23456789101112P(roll)Each person takes turns rolling two dice. If the sum is odd, the person playing odds gets points equal to the sum of the roll. If the sum is even, the person playing evens gets points equal to the sum of the roll. Note that the points earned is independent of who is rolling the dice.If Jessica is challenged to a game of Sums, which statement below is accurate in every aspect in guiding her to the correct choice of choosing to play odds or evens?

Question illustration
A
E(evens) will be more because there are more even numbers that result from rolling two dice. Therefore, Jessica should play evens.
B
E(odds) will be more because the probability for each odd number being rolled is greater. Therefore, Jessica should play odds.
C
E(evens) will be more because the value of the even numbers on the dice are more. Therefore, Jessica should play evens.
D
E(evens) = E(odds) because the different probabilities and values end up balancing out, creating a fair game. Therefore, Jessica may choose whichever she likes.
12

A fair, six-sided number cube has the numbers 2, 2, 4, 4, 6, 6 on its faces. Sarah rolls this number cube 10 times and records the number of times a 2 is rolled.Have the conditions for a binomial setting been met for this scenario?

A
Yes, all four conditions in BINS have been met.
B
No, the rolls of a number cube are not independent of one another.
C
No, this is not a fair number cube because each outcome shows on more than one face.
D
No, without any odd-numbered faces, we cannot determine the probability of rolling a 2.
15

Let A represent the battery life of a brand A laptop, and let B represent the battery life of a brand B laptop. The mean difference in battery life between these two brands of laptops, D = A – B, is –3.25 hours. What is the correct interpretation of this value?

A
On average, brand B gains 3.25 hours of battery life daily.
B
On average, brand A loses 3.25 hours of battery life daily.
C
Both brands are typically losing 3.25 hours of battery life daily.
D
On average, brand B’s battery life lasts 3.25 hours longer than brand A.
19

Standardized tests for certain subjects, given to high school students, are scored on a scale of 1 to 5. Let A represent the score on a randomly selected exam for subject A and let B represent the score on a randomly selected exam for subject B. The distributions of scores for each subject’s standardized tests are displayed in the table and the histograms.

Question illustration
A
Both distributions are roughly unimodal symmetric.
B
Subject A’s distribution is skewed right and subject B’s distribution is skewed left.
C
Subject A’s distribution is roughly unimodal symmetric and subject B’s distribution is skewed left.
D
Subject A’s distribution is roughly unimodal symmetric and subject B’s distribution is skewed right.

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