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Ket [755]
2 years ago
9

The number of texts per day by students in a class is normally distributed with a 

Mathematics
1 answer:
kobusy [5.1K]2 years ago
5 0

Answer:

1, 2, 6

Step-by-step explanation:

The z score shows by how many standard deviations the raw score is above or below the mean. The z score is given by:

z=\frac{x-\mu}{\sigma} \\\\where\ x=raw\ score,\mu=mean, \ \sigma=standard\ deviation

Given that mean (μ) = 130 texts, standard deviation (σ) = 20 texts

1) For x < 90:

z=\frac{x-\mu}{\sigma} \\\\z=\frac{90-130}{20} =-2

From the normal distribution table, P(x < 90) = P(z < -2) = 0.0228 = 2.28%

Option 1 is correct

2) For x > 130:

z=\frac{x-\mu}{\sigma} \\\\z=\frac{130-130}{20} =0

From the normal distribution table, P(x > 130) = P(z > 0) = 1 - P(z < 0) = 1 - 0.5 = 50%

Option 2 is correct

3) For x > 190:

z=\frac{x-\mu}{\sigma} \\\\z=\frac{190-130}{20} =3

From the normal distribution table, P(x > 3) = P(z > 3) = 1 - P(z < 3) = 1 - 0.9987 = 0.0013 = 0.13%

Option 3 is incorrect

4)  For x < 130:

z=\frac{x-\mu}{\sigma} \\\\z=\frac{130-130}{20} =0

For x > 100:

z=\frac{x-\mu}{\sigma} \\\\z=\frac{100-130}{20} =-1.5

From the normal table, P(100 < x < 130) = P(-1.5 < z < 0) = P(z < 0) - P(z < 1.5) = 0.5 - 0.0668 = 0.9332 = 93.32%

Option 4 is incorrect

5)  For x = 130:

z=\frac{x-\mu}{\sigma} \\\\z=\frac{130-130}{20} =0

Option 5 is incorrect

6)  For x = 130:

z=\frac{x-\mu}{\sigma} \\\\z=\frac{160-130}{20} =1.5

Since 1.5 is between 1 and 2, option 6 is correct

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Every piece of chicken costs $1.00.
abruzzese [7]

Answer:

5

Step-by-step explanation:

because if each piece of chicken is 1 dollar she would just have to multiply 1×5

4 0
2 years ago
1/4 divided By 2 Show Your Work On How You Got The Answer
EastWind [94]
1/4 / 2 = 1/4*2 = 1/8
8 0
3 years ago
There are (4^9)^5 ⋅ 4^0 books at the library. What is the total number of books at the library?
seraphim [82]
Do (4^9)^5 first, when an exponent is in a parenthesis with another exponent outside, you multiply them which makes 4^45. Then we multiply 4^0 but this time we add the exponent because there’s no parentheses, which gives you 4^45.
8 0
3 years ago
At 8:00 a.m., there were t inches of snow on the ground. At 5:00 p.m., there were 3t inches of snow on the ground. How many more
Anastaziya [24]

we conclude that at 5:00 p.m. there are 8 more inches of snow than at 8:00 a.m.

<h3>How many more inches of snow were on the ground at 5:00 p.m. than at 8:00 a.m.?</h3>

We know that at 8:00 a.m. there were t inches of snow in the ground.

At 5:00 p.m. there were 3t inches of snow in the ground.

Then the difference between the heights of the snow is:

3t- t = 2t

And we know that at 5:00 p.m. there were 12 inches of snow then we can solve the linear equation for t:

3t = 12in

t = (12in)/3 = 4 in

Replacing that in the difference of heights:

2t = 2*4in = 8in

From this, we conclude that at 5:00 p.m. there are 8 more inches of snow than at 8:00 a.m.

If you want to learn more about linear equations:

brainly.com/question/1884491

#SPJ1

3 0
2 years ago
Can you help me find x
kifflom [539]
X = 30

hope that  helps

180 - 108 = 72

180 - 72 -43 = 65

triangle on the left 
Angles = 43,65,72

triangle on the right

180 - 65 = 115

180 - 115 - 35 = 30
so angles of triangle on the right = 30, 35, 115

x = 30 (vertical angles with the other angle of triangle on the right)



7 0
3 years ago
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