How big will the Universe be in 999 nonillion years?

48. Reading Rates The reading speed of sixth-grade students is approximately normal, with a mean speed of 125 words per minute a

son4ous [18]

Answer:

The reading speed of a sixth-grader whose reading speed is at the 90th percentile is 155.72 words per minute.

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.

In this problem, we have that:

$\mu = 125, \sigma = 24$

What is the reading speed of a sixth-grader whose reading speed is at the 90th percentile

This is the value of X when Z has a pvalue of 0.9. So it is X when Z = 1.28.

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

$1.28 = \frac{X - 125}{24}$

$X - 125 = 1.28*24$

$X = 155.72$

The reading speed of a sixth-grader whose reading speed is at the 90th percentile is 155.72 words per minute.

4 0

3 years ago

Read 2 more answers

Negative fractions on the number line

goblinko [34]

The answer is D
Let me know if it’s right!

8 0

3 years ago

Read 2 more answers

Find the distance between the points (1, 7) and (10, 1) Please help:)

klio [65]

Answer:

The distance between the points (1, 7) and (10, 1) is 10.82 units

Step-by-step explanation:

Distance between two points

The distance between points A(x,y) B(w,z) can be calculated with the formula:

$d=\sqrt{(z-y)^2+(w-x)^2}$

We are given the points (1,7) and (10,1), let's use their values and compute the required distance:

$d=\sqrt{(1-7)^2+(10-1)^2}$

$d=\sqrt{(-6)^2+(9)^2}$

$d=\sqrt{36+81}=\sqrt{117}\approx 10.82$

The distance between the points (1, 7) and (10, 1) is 10.82 units

7 0

3 years ago

Describe what the line on a graph would look like if it had a constant positive rate.

Nuetrik [128]

Answer:

The line would be straight; it could be vertical or horizontal.

5 0

3 years ago

Can someone help me with these and show the work also?

Snezhnost [94]

QUESTION:

Simplify each expression

ANSWER:

1.) $\green{{- 8n}}$

2.) $\green{{- 2b - 60}}$

3.) $\green{{- 10x - 14}}$

4.) for number 4 study my step-by-step explanation so you can answer that

STEP-BY-STEP EXPLANATION:

1.) First, If the term doesn't have a coefficients, it is considered that the coefficients is 1

WHY?

Learn why:

Why is it considered that the coefficient is 1?

Remember that any term multiplied by $\blue{{1}}$ remains the same :

$\blue{{1}}$ ${× x = x}$

Step 1:

The equality can be read in the other way as a well, so any term can be written as a product of $\blue{{1}}$ and itself:

${x = }$ $\blue{{1}}$ ${× x}$

Step 2:

Usually, we don't need to write multiplacation sign between the coefficient and variable, so the simple form is:

${x = 1x}$

This is why we can write the term without the coefficient as a term with coefficient ${1}$

Now let's go back to solving as what i said if a term doesn't have a coefficient, it is considered that the coefficient is 1

${n - 9n}$

$\red{{1}}$ ${n -9n}$

Second, Collect like terms by subtracting their coefficients

$\red{{1n - 9n}}$

$\red{{( 1 - 9)n}}$

Third, Calculate the difference

how?

Keep the sign of the number with the larger absolute value and subtract the smaller absolute value from larger

$\red{{1 - 9}}$

$\red{{- (9 - 1)}}$

Subtract the numbers

- ( $\red{{9 - 1}}$ )n

- $\red{{8}}$ n

$\green{\boxed{- 8n}}$

2.) First, Distribute - 6 through the parentheses

how?

Multiply each term in the parentheses by - 6

$\red{{- 6(b + 10)}}$

$\red{{- 6b - 6 × 10}}$

Multiply the numbers

- ${6b}$ - $\red{{6 × 10}}$

- ${6b}$ - $\red{{60}}$

Second, Collect like term

how?

Collect like terms by calculating the sum or difference of their coefficient

$\red{{- 6b + 4b}}$

$\red{{(- 6 + 4)b}}$

Calculate the sum

$\red{{(- 6 + 4)}}$ b

$\red{{-2}}$ b

$\green{\boxed{- 2b - 60}}$

3.) First, Distribute 2 through parentheses

how?

Multiply each term in the parentheses by 2

$\red{{2(x - 5)}}$

$\red{{2x - 2 × 5}}$

Multiply the numbers

${2x -}$ $\red{{2 × 5}}$

${2x -}$ $\red{{10}}$

Second, Distribute - 4 through the parentheses

how?

Multiply each term in the parentheses by - 4

$\red{{- 4(3x + 1)}}$

$\red{{- 4 × 3x - 4}}$

Calculate the product

- $\red{{4 × 3}}$ x - 4

- $\red{{12}}$ x - 4

Third, Collect like terms

how?

Collect like terms by subtracting their coefficient

$\red{{2x - 12x}}$

$\red{{(2 - 12)x}}$

Calculate the difference

$\red{{(2 - 12)}}$ x

$\red{{- 10}}$ x

Fourth, Calculate the difference

how?

Factor out the negative sign from the expression

$\red{{- 10 - 4}}$

$\red{{- (10 + 4)}}$

Add the numbers

- ( $\red{{10 + 4}}$ )

- $\red{{14}}$

$\green{\boxed{- 10x - 14}}$

That's all I know sorry but I hope it helps :)

6 0

3 years ago