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morpeh [17]
2 years ago
3

An econometrics class has 80​ students, and the mean student weight is 145 lb. a random sample of four students is selected from

the​ class, and their average weight is calculated. will the average weight of the students in the sample equal​ 145lb?
Mathematics
1 answer:
Tresset [83]2 years ago
4 0
The total weight of 80 students is 80 × 145 = 11600 lb

If a sample of four students taken, their total weight divided by 4 would not necessarily give 145lb. The weight of each of the four students could be from the lightest end of the range or could be from the heaviest end of the range. 
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Stacey has a square piece of cloth. She cuts 3 inches off of the length of the square and 3 inches off of the width. The area of
ratelena [41]

Answer:

The side length of the original square was 6 inches

Step-by-step explanation:

we know that

The area of a square is

A=b^2

where

b is the length side of the square

Let

x ---> the length of the original square

The area of the original square is

A=x^{2}\ in^2

The length of the smaller square is

b=(x-3)\ in

The area of the smaller square is

A=(x-3)^2\ in^2

The area of the smaller square is 1/4 the area of the original square

so

(x-3)^2=\frac{1}{4} x^{2}

solve for x

x^2-6x+9=\frac{1}{4} x^{2}

Multiply by 4 both sides

4x^2-24x+36=x^{2}

4x^2-x^2-24x+36=0\\3x^2-24x+36=0

Solve the quadratic equation by graphing

using a graphing tool

x=2, x=6

see the attached figure

The solution is x=6 in

Remember that the solution must be greater than 3 inches (because Stacey cuts  3 inches off of the length of the square and 3 inches off of the width)

therefore

The side length of the original square was 6 inches

3 0
2 years ago
What is the first step to solve this equation : 11-3x=44
Zolol [24]

Answer:

Subtract 11 from both sides

Step-by-step explanation:

4 0
2 years ago
Read 2 more answers
Minute Maid states that a bottle of juice contains 473 mL. Consumer groups are interested in determining if the bottles contain
olga2289 [7]

Answer:

Option C) The average contents of all bottles of juice in the population, which is 473 mL

Step-by-step explanation:

We are given the following in the question:

Population mean, μ = 473 mL

Sample mean, \bar{x} = 472 mL

Sample size, n = 30

Sample standard deviation, σ = 0.2

First, we design the null and the alternate hypothesis

H_{0}: \mu = 473\text{ mL}\\H_A: \mu < 473\text{ mLinches}

Representation of \mu

  • \mu is the population parameter that represents the population mean.

Thus, for the given situation \mu represents:

Option C) The average contents of all bottles of juice in the population, which is 473 mL

6 0
2 years ago
Simplify square root of (1-sin theta)(1+sin theta)
Vinil7 [7]
Recall the important identities:

i) (a-b)(a+b)= a^{2}- b^{2}, the difference of squares formula.

ii) sin^{2} x+cos^{2}x=1, for any angle x.

Then,

from i)

\sqrt{(1-sin(theta))(1+sin(theta))}= \sqrt{1- sin^{2}(theta) }

then, from ii), we have 

\sqrt{1- sin^{2}(theta) }= \sqrt{cos^{2}(theta) }=cos(theta)


Answer: cos(theta) 

6 0
2 years ago
We went to the market to buy some fruit. We decided to buy some apples, strawberries, and oranges. If we buy 2 apples, 3 boxes o
Ksivusya [100]

Step-by-step explanation:

Let the amount of apples bought be x

Amount of strawberries bought be y and;

amount of oranges bought be z

If we buy 2 apples, 3 boxes of strawberry, and 4 oranges, the fruit would cost $15.30, then this will be expressed as;

2x+3y+4z = 15.30 ........... 1

If we buy 1 box of strawberry, 4 apples, and 2 oranges, the fruit would cost $10.90, this will be expressed as:

4x+y+2z = 10.90 ......... 2

If we buy 1 orange, 5 apples and 2 boxes of strawberry, the fruit would cost $13.70, this is expressed as:

5x+2y+x = 13.70 .......... 3

Solving the three equations simultaneously:

2x+3y+4z = 15.30 ........... 1

4x+y+2z = 10.90 ......... 2

5x+2y+z = 13.70 .......... 3

Reduce the number of equations

multiply equation 1 by 2 and subtract from equation 2

equation 1 * 2 will give:

4x+6y+8z = 30.6 ........... 4

eqn (4)-eqn(2)

6y-y + 8z-2z = 30.6-10.90

5y+6z = 19.7 ......... 5

Also multiply equation 2 by 5 and eqn 5 by 4 and subtract from each other.

eqn(2)* 5 will give:

20x+5y+10z = 54.5 .......... *

eqn(3) * 4 will give

20x+8y+4z = 54.8.......**

Subtsrct ** from *

8y-3y+(4z-10z)= 54.8-54.5

5y-6z = 0.3 .................. 6

Equate 5 and 6 and solve:

5y+6z = 19.7 ......... 5

5y-6z = 0.3 .................. 6

subtract:

6z+6z = 19.7+0.3

12z = 20

z = 20/12

z = 1.67

Substitute z = 1.67 into eqn 6

5y-6(1.67) = 0.3

5y - 10 = 0.3

5y = 10.3

y = 10.3/5

y = 2.06

Substitute z = 1.67 and y = 2.06 into equation 1

From 1:

2x+3y+4z = 15.30

2x+3(2.06)+4(1.67) = 15.30

2x+6.18+6.68 = 15.30

2x+12.86 = 15.30

2x = 15.30-12.86

2x = 2.44

x = 2.44/2

x = 1.22

<em>Therefore 1 apple costs $1.22, 1 strawberry costs $2.06 and 1 orange costs $1.67</em>

3 0
2 years ago
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