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# ECO250Unit 4 In-Class ExerciseWhat is a random

variable? Give an example.

Suppose you are shopping online for a new toy for your dog. As you look at the product reviews, you see the following distribution of ratings. Use this table for questions 2-5.

1. Sketch a data visualization of the distribution of stars.

1. What is the probability that a randomly chosen reviewer gave the dog toy 3 stars? What is the probability that a randomly chosen reviewer gave the dog toy 3 or fewer stars?

1. Find the expected value for the number of stars.

1. Find the standard deviation of the number of stars.

1. Write down the formula for the binomial distribution. What do n, x, and represent in the formula? What does n! mean?

1. As you shop for dog treats, a seller advertises that 95% of veterinarians recommend their treats. Suppose you randomly choose 10 veterinarians and ask whether they recommend this seller's treats.
2. What is the probability that exactly nine veterinarians in your sample recommend the seller's treats?

1. What is the probability that more than eight veterinarians in your sample recommend the seller's treats?

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Suppose you are shopping online for a new toy for your dog. As you look at the
product reviews, you see the following distribution of ratings. Use this table for
questions 2-5.
Body
Stars Frequenc
UT
Style
Layout
More
W A
w
- N
Font
N
Trebuchet MS (Calibri)
5
12 pt
B
U
# v
O
2. Sketch a data visualization of the distribution of stars.
Character Styles
None
Alignment
E
3. What is the probability that a randomly chosen reviewer gave the dog toy 3 stars?
What is the probability that a randomly chosen reviewer gave the dog toy 3 or
fewer stars?
Spacing
1.0 - Single
Bullets &amp; Lists
None
4. Find the expected value for the number of stars.

125% v
T
1 v
?
View
Zoom
Insert
Table
Chart
Text
Shape
Media Comment
Share
Tips
Format Document
Text
Body
Style
Layout
More
Font
Trebuchet MS (Calibri)
12 pt
5. Find the standard deviation of the number of stars.
B
U
# v
O
Character Styles
None
Alignment
E
6. Write down the formula for the binomial distribution. What do n, x, and represent
in the formula? What does n! mean?
Spacing
1.0 - Single
Bullets &amp; Lists
None
7. As you shop for dog treats, a seller advertises that 95% of veterinarians
recommend their treats. Suppose you randomly choose 10 veterinarians and ask
whether they recommend this seller's treats.
a. What is the probability that exactly nine veterinarians in your sample
recommend the seller's treats?
b. What is the probability that more than eight veterinarians in your sample
ats?

3). p=0.40 4). E(x)=3.5 5). standard... View the full answer

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