Question

The ages of a large group of people have an average of 52 years and an SD of 6 years. The average annual income of the people is $48,000 and the SD is $27,000. The correlation between the two variables is 0.45.

1A

This problem is worth 1 point.

The r.m.s. error of regression for estimating income based on age is closest to:


5.4 thousand dollars
5.4 years
24.11 thousand dollars
24.11 years

Answer 1

did any one had solve it

Answer 2

The r.m.s error of the regression line is
\[\sqrt{(1-r ^{2}})\times S.D.\ of\ income=\sqrt{(1-0.45^{2}}\times 27000=$24,111\]

Answer 3

thank you very much

Answer 4

You're welcome :)

Answer 5

If you have any questions allso feel free bro

Answer 6

Are you also member of edx

Answer 7

No, I am not a member of edx.

Answer 8

Is the scatter diagram of the two variables football shaped?


No.
Yes.
Maybe, or maybe not; there is not enough information to decide.

Answer 9

A scatter diagram is football-shaped or the points form a cloud on the scatter
diagram if most of the points on the graph fall within the region of an elliptical
shape.
The annual income has a very large standard deviation relative to the average, Therefore the scatter diagram is not football-shaped.

Answer 10

Thanks very good exlonation

Answer 11

One question sir you are from where

Answer 12

The weights of newborns at a hospital have an average of 7 lb and an SD of 1.2 lb. The average head circumference of the newborns is 14 inches and the SD is 0.5 inches. The correlation between the two variables is 0.55 and the scatter diagram is football shaped. The regression line for estimating head circumference based on weight is drawn on the scatter diagram, with weight on the horizontal axis.
3A : 2.0 POINTS

For about 50% of the newborns, the regression estimate of head circumference based on weight is correct to within _____________ inches. Fill in the blank.

Answer 13

If the scatter diagram is football-shaped, the r.m.s. error can be used like a standard deviation for the regression line.
Approximately 50% of the points will be between
\[the\ regression\ estimate \pm 0.675(r.m.s.\ error)\]
\[r.m.s.\ error=\sqrt{(1-r ^{2})}\times S.D.\ head\ circumference=0.835\times 0.5=0.4175\ inch\]
For about 50% of the newborns, the regression estimate of head circumference based on weight is correct to within (0.675 * 0.4175) inch.

Answer 14

For about what percent of the newborns does the regression line overestimate head circumference by more than 0.5 inches?


3C : 3.0 POINTS

Of the newborns who weigh 8 pounds, about what percent have head circumferences larger than 15 inches?

Answer 15

For about what percent of the newborns does the regression line overestimate head circumference by more than 0.5 inches?
z * (r.m.s. error) = 0.5
z = 0.5/0.4175 = 1.1976
Reference to a standard normal distribution table shows that about 11.5% will have head diameters overestimated.

Answer 16

answears are wrong bro

Answer 17

sorry they are right
what about 15 inches

Answer 18

what about part c

Answer 19

Had done it already very simple

Answer 20

The ages of a large group of people have an average of 52 years and an SD of 6 years. The average annual income of the people is $48,000 and the SD is $27,000. The correlation between the two variables is 0.45.

1A

This problem is worth 1 point.

The r.m.s. error of regression for estimating income based on age is closest to:



24.11 thousand dollars(wright answear)


1B : 2.0 POINTS

Is the scatter diagram of the two variables football shaped?


Yes.(right answear)


Problem 2A


The calculations are wrong.(right answear)




Problem 2B


There is a non-linear relation between the two variables in the regression. (right answear)


Problem2C


Regresion looks ok (right answear)



Problem 2D


The regression looks OK(right answear)

Problem 2E


The calculations are wrong.(right answear)

3A : 2.0 POINTS

For about 50% of the newborns, the regression estimate of head circumference based on weight is correct to within _____________ inches. Fill in the blank.

0.28181 correct


3B : 2.0 POINTS

For about what percent of the newborns does the regression line overestimate head circumference by more than 0.5 inches?

11.5 correct

3C : 3.0 POINTS

Of the newborns who weigh 8 pounds, about what percent have head circumferences larger than 15 inches?

3.2 correct

Answer 21

Thank u

Answer 22

An orchestra consists of 25 members. The youngest member is 32 years old. She leaves and is replaced by a new member who is 30 years old.

1A

By how much does the replacement change the average age of the members of the orchestra?

[Note on answer format: Calculate your answer in years. If you think the average is unchanged, enter 0. If you think it goes up by 10.5 years, enter 10.5. If you think it goes down by 10.5 years, enter -10.5.]

is -10.5???

Answer 23

@rocio.soto estas son las respuestas:
A -0.08
B 0

Answer 24

ThanK You

Answer 25

Please, Help me with this questions

The final exam is “graded on a curve,” with the top 20% of the students on the final receiving an A grade on the exam. Is the set of students who receive an A on the exam based on the new final exam scores different from the set of students who received an A on the exam based on the old final exam scores?
The correlation between the new final scores and the old final scores is:


-1
-0.63
0
0.63
1
impossible to determine based on the information given.
possible to determine based on the information given, and not equal to -1, -0.63, 0, 0.63 or 1.

The correlation between the new final scores and the midterm scores is:


-1
-0.63
0
0.63
1
impossible to determine based on the information given.
possible to determine based on the information given, and not equal to -1, -0.63, 0, 0.63 or 1.

Answer 26

the answer is 1 and next is 0.63. please help me with this questionThe scatter diagram of midterm scores and final scores in a large class is football shaped. For about 80% of the students, the regression estimate of final score based on midterm score is correct to within 15 points.

For about 95% of the students, the regression estimate of final score based on midterm score is correct to within ___________ points.

Answer 27

A standard deck consists of 52 cards, distributed as follows:

There are 13 cards in each of 4 suits: hearts, diamonds, spades, and clubs. Hearts and diamonds are red. Spades and clubs are black.
In each suit there are 13 ranks: Ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, King.
In Exercises 2A through 2E, assume that cards are dealt from a well-shuffled deck; that is, cards are dealt at random without replacement.
PROBLEM 2A

This Problem is worth 1 Point

The "face" cards are those that have a person’s face on them: Jack, Queen, or King. One card is dealt. Find the chance that it is a face card.


PROBLEM 2B

This Problem is worth 1 Point
One card is dealt. Find the chance that its color is black and its rank is an even number.

PROBLEM 2C

This Problem is worth 1 Point
One card is dealt. Find the chance that its color is red or its rank is an even number.

PROBLEM 2D

This Problem is worth 1 Point
A poker hand (5 cards) is dealt. Find the chance that the cards are all hearts.

PROBLEM 2E

This Problem is worth 1 Point
A poker hand (5 cards) is dealt. Find the chance that the cards are all of the same suit. [This is sometimes called a “flush.”]


There are 5 people in a room. Make the following simplifying assumptions about their birthdays:

Ignore leap years; assume 365 days in the year.
For each person, assume that the chance he/she is born on a specified day is 1/365.
No twins! Assume that the chance that someone is born on a specified day is not affected by other people’s birthdays.


PROBLEM 4B

This Problem is worth 1 Point
Find the chance of a "match": that is, at least two people in the room have the same birthday.

PROBLEM 4C

This Problem is worth 1 Point
Repeat 4B for a room in which there are 400 people.

There are 26 letters in the English alphabet. Letters are picked one by one at random, so that each letter has the same chance of appearing as any other letter, regardless of which letters have appeared or not appeared.

PROBLEM 5A

This Problem is worth 1 Point
Six letters are picked. Find the chance that the sequence that appears is RANDOM, in that order.


PROBLEM 5B

This Problem is worth 1 Point
Six letters are picked. Find the chance that they can be arranged to form the word RANDOM.


A two-day conference is going to be held in a city. The leading newspaper in the city says there is a 10% chance of rain on the first day of the conference and a 40% chance of rain on the second day.

PROBLEM 6A

This Problem is worth 1 Point
If the newspaper’s figures are correct, the chance that it rains in the city during the conference is:


at least 0%, but we can’t get a better lower bound with the information given.
at least 10% but it might be less than 40%.
at least 40%.


PROBLEM 6B

This Problem is worth 1 Point
If the newspaper’s figures are correct, the chance that it rains in the city during the conference is


at most 10%.
at most 40%.
at most 50%.
at most 100%; that’s the best upper bound we can get based on the information given.

Answer 28

2A : 3/13 ???