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aliina [53]
3 years ago
13

A field test for a new exam was given to randomly selected seniors. The exams were graded, and the sample mean and sample standa

rd deviation were calculated. Based on the results, the exam creator claims that on the same exam, nine times out of ten, seniors will have an average score within 5% of 75%.
Is the confidence interval at 90%, 95%, or 99%? What is the margin of error? Calculate the confidence interval and explain what it means in terms of the situation.
Mathematics
1 answer:
Veronika [31]3 years ago
3 0

Answer:

90% is the answer for confidence interval

Step-by-step explanation:

Given that a field test for a new exam was given.75±0.05(75)

i.e. margin of error =0.05(75)=

The population under study was the seniors. Sample mean and std dev were calculated

Stated that the exam creator ased on the results, that on the same exam, 9 out of 10 seniors will have an average score within 5% of 75%

This implies that 9 out of 10 means in percent 90%

Hence the confidence interval is 90%

SInce 5% of 75 is given the range is 75±(75)

Margin of error =3.75

Confidence interval =(75±3.75)

=(71.25,78.75)

We can interpret this we are 90% confident that  as sample sizes increase, and samples are drawn at random the average grades of seniors would lie between 71.25 and 78.75

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Which linear equation has no solution?
olga_2 [115]

Answer:

Option A

Step-by-step explanation:

Given:

  • a. 3x-5= 3x + 5
  • b. 3x-5= 3x - 5
  • c. 3x - 5 = 2x+5
  • d. 3x-5 = 2x + 10

To find:

  • Which one of the linear equations have no solution.

Solution:

a)  3x-5= 3x + 5

Add 5 to both sides

3x-5= 3x + 5

3x - 5 + 5 = 3x + 5 + 5

Simplify

(Add the numbers)

3x - 5 + 5 = 3x + 5 + 5

3x = 3x + 5 + 5

(Add the numbers)

3x  = 3x + 5 + 5

3x = 3x + 10

Subtract 3x from both sides

3x = 3x + 10

3x - 3x = 3x + 10 - 3

Simplify

(Combine like terms)

3x -3x = 3x + 10 - 3

0 = 3x + 10 - 3

(Combine like terms)

0 = 3x + 10 - 3

0 = 10

The input is a contradiction: it has no solutions

b)  3x-5= 3x - 5

Since both sides equal, there are infinitely many solutions.

c)  3x - 5 = 2x+5

Add 5 to both sides

3x = 2x + 5 + 5

Simplify  2x + 5 + 5 to 2x + 10

3x = 2x + 10

Subtract 2x from both sides

3x - 2x = 10

Simplify 3x - 2x to x.

x = 10

d) 3x-5 = 2x + 10

Add 5 to both sides

3x = 2x + 10 + 5

Simplify 2x + 10 + 5 to 2x + 15

3x = 2x + 15

Subtract 2x from both sides

3x - 2x = 15

Simplify 3x -2x to x.

x = 15

--------------------------------------------

Answer:

As you can see all c and d both have solutions, eliminating them as options. Option B has infinite solutions leaving Option A which has no solutions.

Therefore, <u><em>Option A</em></u> is the linear equation that has no solution.

3 0
2 years ago
Read 2 more answers
What is the solution to |x + 2| &lt; 1?
Katyanochek1 [597]

Answer:

-3 <x <-1

Step-by-step explanation:

|x + 2| < 1

There are two solutions, one positive and one negative ( remember to flip the inequality for the negative)

x+2 <1    and  x+2 > -1

Subtract 2 from each side

x+2-2 < 1-2  and  x+2-2 > -1-2

x < -1      and       x >-3

-3 <x <-1

8 0
3 years ago
The half-life of strontium -90 is approximately 29 Year’s . How much of a 150 g sample of strontium-90 will remain after 116 yea
marin [14]
The half-life is 29 years.
116 : 29 = 4
So we will have 4 periods of half-life:
( 1/2 )^4 = 1/16
150 g * 1/16 = 9.375 g
Answer:
9.375 g of strontium -90 will remain after 116 years.
3 0
3 years ago
Gianna was out at a restaurant for dinner when the bill came. Her dinner came to
nikitadnepr [17]

Answer:

12 percent

Step-by-step explanation:

The tip is 24.64 - 22 = 2.64

2.64 / 22 = 0.12

4 0
2 years ago
Three siblings are one year apart inage. If the oldest is x years old, what is the average of their ages?
Yuliya22 [10]

Answer:

x - 1

Step-by-step explanation:

x

x - 1

x - 2

x + (x - 1) + ( x - 2)

3x - 3

3(x - 1)

Average

3(x - 1)/3

x - 1

6 0
3 years ago
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