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Ghella [55]
2 years ago
8

A teacher collected information from a class of 25 students about the time, in hours, they spent studying the previous week and

the time, in hours, they spent on the Internet the previous week. The value of the correlation coefficient between hours spent studying and hours spent on the Internet was −0.72. If the teacher changes the units of each variable from hours to minutes, what will be the value of the correlation coefficient between minutes studying and minutes spent on the Internet?
Mathematics
1 answer:
amm18122 years ago
5 0

Answer:

Correlation will not change.

Correlation coefficient = -0.72

Step-by-step explanation:

We are given the following in the question:

Correlation coefficient between hours spent studying and hours spent on the Internet = -0.72

Properties of correlation coefficient:

  • Correlation is a technique that help us to find or define a relationship between two variables.
  • It is a measure of linear relationship between two quantities.
  • It is not affected by the units of the variable or change in units of the variable.

Thus, if the units of each variable is changed from hours to minutes, the correlation coefficient remains the same between minutes studying and minutes spent on the Internet.

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For questions 2-5, the number of pieces in a regular bag of Skittles is approximately normally distributed with a mean of 38.4 a
aleksley [76]

Answer:

a. -1.60377

b. 0.25451

c. 0.344

d. Option b) 78th

Step-by-step explanation:

The number of pieces in a regular bag of Skittles is approximately normally distributed with a mean of 38.4 and a standard deviation of 2.12.

a)What is the z-score value of a randomly selected bag of Skittles that has 35 Skittles? a) 1.62 b) -1.62 c) 3.40 d) -3.40 e)1.303.

The formula for calculating a z-score is is z = (x-μ)/σ,

where x is the raw score

μ is the population mean

σ is the population standard deviation.

z = 35 - 38.4/2.12

= -1.60377

Option b) -1.62 is correct

b) What is the probability that a randomly selected bag of Skittles has at least 37 Skittles? a) .152 b) .247 c) .253 d).747e).7534. .

z = (x-μ)/σ

Mean of 38.4 and a standard deviation of 2.12.

z = (37 - 38.4)/2.12

= -0.66038

P-value from Z-Table:

P(x<37) = 0.25451

The probability that a randomly selected bag of Skittles has at least 37 Skittles is 0.25451

Option c) .253 is.correct

c) What is the probability that a randomly selected bag of Skittles has between 39 and 42 Skittles? a) .112 b) .232 c) .344 d).457 e).6125.

z = (x-μ)/σ

Mean of 38.4 and a standard deviation of 2.12.

For 39 Skittles

z = (39 - 38.4)/2.12

= 0.28302

Probability value from Z-Table:

P(x = 39) = 0.61142

For 42 Skittles

z = (42 - 38.4)/2.12

= 1.69811

Probability value from Z-Table:

P(x = 42) = 0.95526

The probability that a randomly selected bag of Skittles has between 39 and 42 Skittles is:

P(x = 42) - P(x = 39

0.95526 - 0.61142

0.34384

= 0.344

Option c is.correct

d) What is the percentile rank of a randomly selected bag of Skittles that has 40 Skittles in it? a)82nd b) 78th c) 75th d)25th e)22nd

z = (x-μ)/σ

Mean of 38.4 and a standard deviation of 2.12.

z = (40 - 38.4)/2.12

= 0.75472

P-value from Z-Table:

P(x = 40) = 0.77479

Converting to percentage = 0.77479× 100

= 77. 479%

≈ 77.5

Percentile rank = 78th

7 0
2 years ago
1. Miguel is playing a game in which a box contains four chips with numbers written on them. Two of the chips have the number 1,
zzz [600]

Answer:


Step-by-step explanation:

Given that Miguel is playing a game

The box contains 4 chips, 2 with number 1, and other two differntly numbered as 3 and 5.

OUt of these 4, 2 chips are drawn

P(drawing same number) = 2C2/4C2 =\frac{1}{6}

Prob (drawing differnt numbers) = 1-1/6 =\frac{5}{6}

Hence prob of winning 2 dollars = \frac{1}{6}

Prob of losing 1 dollar = \frac{5}{6}

b) Expected value = sum of prob x amount won

= \frac{1}{6}2+\frac{5}{6}(-1)=-\frac{1}{2}

c) Miguel can expect to lose 1/2 dollars for every game he plays

d) If it is to be a fair game expected value =0

i.e. let the amount assigned be s

Then \frac{1}{6}s-\frac{5}{6}=0\\s=5

6 0
2 years ago
Read 2 more answers
If e = 9 cm and f = 40 cm, what is the length of g?
rewona [7]

(9,40,41) is a Pythagorean Triple, farther down the list than teachers usually venture.

Answer: D. 41 cm

There's a subset of Pythagorean Triples where the long leg is one less than the hypotenuse,

a^2+b^2 = (b+1)^2

a^2 + b^2 = b^2 + 2b +1

a^2=2b+1

So we get one for every odd number, since the square of an odd number is odd and the square of an even number is even.

b = (a^2 - 1)/2

a=3, b=(3^2-1)/2=4, c=b+1=5

a=5, b=(5^2-1)/2 =12, c = 13

a=7, b=24, c=25

a=9, b=40, c=41

a=11, b=60, c=61

a=13, b=84, c=85

It's good to be able to recognize Pythagorean Triples when we see them.  

Otherwise we'd have to work the calculator:

√(9² + 40²) = √1681 = 41

8 0
2 years ago
. Cara is playing a game. For each dart she can toss onto a board, she
Kaylis [27]
She will need 12 seconds because -20•12=-240
6 0
2 years ago
If x and y are two positive real numbers such that x 2 +4y 2 =17 and xy =2, then find the value of x- 2y. a. 3 b. 4 c. 8 d. 9
Dafna11 [192]

Answer: The value of x- 2y is a. \pm 3.

Step-by-step explanation:

Given:  x and y are two positive real numbers such that x^2+4y^2=17   and xy= 2 .

Consider (x-2y)^2=x^2-2(x)(2y)+(2y)^2\ \ \ [(a+b)^2=(a^2-2ab+b^2)]

=x^2-4xy+4y^2

=x^2+4y^2-4(xy)

Put  x^2+4y^2=17   and xy= 2 , we get

(x-2y)^2=17-4(2)=17-8=9

\Rightarrow\ (x-2y)^2=9

Taking square root on both sides , we get'

x-2y= \pm3

Hence, the value of x- 2y is a. \pm 3.

7 0
2 years ago
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