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2 years ago

7

A lawn with an area of 300 square feet needs 1/2 pound of grass seed. How many pounds of grass seed are needed for a lawn that i

s 60 feet long and 20 feet wide?

1 answer:

Anna [14]2 years ago

8 0

60x20=1200
1200/300=4
4x1/2=4/2=2 pounds of grass seed

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Consider a normal distribution curve where the middle 85 % of the area under the curve lies above the interval ( 8 , 14 ). Use t

NeTakaya

Answer:

$\mu = 11$

$\sigma = 2.08$

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Middle 85%.

Values of X when Z has a pvalue of 0.5 - 0.85/2 = 0.075 to 0.5 + 0.85/2 = 0.925

Above the interval (8,14)

This means that when Z has a pvalue of 0.075, X = 8. So when $Z = -1.44, X = 8$ . So

$Z = \frac{X - \mu}{\sigma}$

$-1.44 = \frac{8 - \mu}{\sigma}$

$8 - \mu = -1.44\sigma$

$\mu = 8 + 1.44\sigma$

Also, when X = 14, Z has a pvalue of 0.925, so when $X = 8, Z = 1.44$

$Z = \frac{X - \mu}{\sigma}$

$1.44 = \frac{14 - \mu}{\sigma}$

$14 - \mu = 1.44\sigma$

$1.44\sigma = 14 - \mu$

Replacing in the first equation

$\mu = 8 + 1.44\sigma$

$\mu = 8 + 14 - \mu$

$2\mu = 22$

$\mu = \frac{22}{2}$

$\mu = 11$

Standard deviation:

$1.44\sigma = 14 - \mu$

$1.44\sigma = 14 - 11$

$\sigma = \frac{3}{1.44}$

$\sigma = 2.08$

7 0

2 years ago

1111111111111111111111

Sergio [31]

11111111111111111-111111111-1

4 0

2 years ago

Read 2 more answers

Gregorio took two tests. Find his z-score for each test. (Remember: The number of standard deviations between a score and the me

never [62]

I found the missing parts of this question.
Test A
<span>Gregorio’s score </span><span>62 </span>
<span>Mean score </span><span>80 </span>
<span>Standard deviation </span><span>6 </span>

<span>Test B </span>
<span>Gregorio's score </span><span>70 </span>
<span>Mean score </span><span>90 </span>
<span>Standard deviation </span><span>10 </span>

<span>a. </span><span>Test A: 3; Test B: 2; Test A </span>
<span>c. </span><span>Test A: –2; Test B: –3; Test A </span>
<span>b. </span><span>Test A: –3; Test B: –2; Test B </span>
<span>d. </span><span>Test A: –3; Test B: –2; Test A
</span>

Refer to the attachment for the formula of z score:

test A: z = (62-80)/6 = -18/6 = -3
test B: z = (70-90)/10 = -20/10 = -2

B. <span>Test A: –3; Test B: –2; Test B </span>

5 0

3 years ago

What is the value of the expression below?<br><br> −20÷5

Lera25 [3.4K]

The answer would be -4
Hope this helps

5 0

3 years ago

Read 2 more answers

This is for a retake for geometry pls help

Alexeev081 [22]

Answer:

B. 40, 51.5, 88.5

Step-by-step explanation:

(5x - 4) + (2x + 3) + (3x- 4) = 180

10x - 5 = 180

10x = 185

x= 18.5

Substitute

5(18.5) - 4 = 88.5

2(18.5) + 3 = 40

3(18.5) - 4 = 51.5

5 0

2 years ago