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3 years ago

Solve for substitution x-2y+z=-11 3x+2y-z=7 -x+2y+4z=-9

Mathematics

1 answer:

Alla [95]3 years ago

6 0

Answer:

Unit rate miles per day is, 3

Step-by-step explanation:

Unit rate are defined as the rate are expressed as quantity of 1 such that 2 miles per hour or 5 km per hour.

As per the given statement: A construction crew built 1/2 miles of road in 1/6 days

by unit rate definition;

After substituting the given values we have

⇒

Therefore, unit rate miles per day is, 3

Step-by-step explanation:

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The time for a visitor to read health instructions on a Web site is approximately normally distributed with a mean of 10 minutes

klio [65]

Answer:

a) The mean is 10 and the variance is 0.0625.

b) 0.6826 = 68.26% probability that the mean time of the visitors is within 15 seconds of 10 minutes.

c) 10.58 minutes.

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal Probability Distribution

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score 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 p-value, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

Normally distributed with a mean of 10 minutes and a standard deviation of 2 minutes.

This means that $\mu = 10, \sigma = 2$

Suppose 64 visitors independently view the site.

This means that $n = 64, = \frac{2}{\sqrt{64}} = 0.25$

a. The expected value and the variance of the mean time of the visitors.

Using the Central Limit Theorem, mean of 10 and variance of (0.25)^2 = 0.0625.

b. The probability that the mean time of the visitors is within 15 seconds of 10 minutes.

15 seconds = 15/60 = 0.25 minutes, so between 9.75 and 10.25 seconds, which is the p-value of Z when X = 10.25 subtracted by the p-value of Z when X = 9.75.

X = 10.25

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

By the Central Limit Theorem

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

$Z = \frac{10.25 - 10}{0.25}$

$Z = 1$

$Z = 1$ has a p-value of 0.8413.

X = 9.75

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

$Z = \frac{9.75 - 10}{0.25}$

$Z = -1$

$Z = -1$ has a p-value of 0.1587.

0.8413 - 0.1587 = 0.6826.

0.6826 = 68.26% probability that the mean time of the visitors is within 15 seconds of 10 minutes.

c. The value exceeded by the mean time of the visitors with probability 0.01.

The 100 - 1 = 99th percentile, which is X when Z has a p-value of 0.99, so X when Z = 2.327.

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

$2.327 = \frac{X - 10}{0.25}$

$X - 10 = 2.327*0.25$

$X = 10.58$

So 10.58 minutes.

6 0

2 years ago

Shapes that always have perpendicular lines

amm1812

A couple of shapes that have perpendicular lines are right triangles, and rectangles.

6 0

2 years ago

I) Find the volume in terms of pie

SVETLANKA909090 [29]

Answer:

i) pi×4500 cm³

ii) pi×600 cm²

iii) 14 liters

Step-by-step explanation:

in general : the diameter is 30 cm, the radius is half of that (15 cm)

the volume of a cylinder is base area times height.

Vc = pi×r²×h = pi×15²×20 = pi×225×20 = pi×4500 cm³

ii)

similar to volume, the side "mantle" area of the cylinder is the circumference of the base area times height.

surface area of the cylinder mantle is

Scm = 2×pi×r×h = 2×pi×15×20 = pi×30×20 = pi×600 cm²

iii)

for this we need now to do the multiplication with pi and then convert the cm³ to liters.

1 liter = a cube of 10 cm side length = 10×10×10 = 1000 cm³

pi×4500 = 14137.17 cm³ = 14.13717 liters or rounded 14 liters

3 0

3 years ago

Lol someone help me please

seraphim [82]

Ooo! I love these! Ok so your IQR is C or D. I might have my calculations wrong if so. Sorry!

6 0

3 years ago

Create and solve a linear equation that represents the model, where circles and a square are shown evenly balanced on a balance

Maslowich

A linear equation that represents the model is: x + 6 = 10; x = 4

<h3>How to solve linear equations?</h3>

Let us first define the variables based on the attached image of the ball balance:

Let x = number of balls that contains the square.

On the left side, we have; square + 6 balls

On the right side, we have; 10 balls

To balance this, we have;

x + 6 = 10

x = 10-6

x = 4

Thus, a linear equation that represents the model is:

x + 6 = 10; x = 4

Read more about Linear equations at; brainly.com/question/9406333

#SPJ1

3 0

2 years ago