30 points Someone help im very confused.

What is 7- (7r+7)= 6r+7

Sliva [168]

Answer:

r= 43/13

Step-by-step explanation:

8 0

3 years ago

Which expression is equal to 2xx−2−x+3x+5?

iren2701 [21]

Answer:

It's the fourth one

4 0

3 years ago

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A random sample of 10 subjects have weights with a standard deviation of kg. What is the variance of their weights? be sure to

Vera_Pavlovna [14]

The variance of their weights is 128.87270 kg².

It is required to find the variance of their weights.

<h3>What is standard deviation ?</h3>

A standard deviation (or σ) is a measure of how dispersed the data is in relation to the mean. Low standard deviation means data are clustered around the mean, and high standard deviation indicates data are more spread out.

Given:

Let n=sample size=10 subjects

Standard deviation=11.352211.3522 kg

Using this formula

Variance=(Standard deviation)²

By the formula we get,

Variance=(11.352211.3522 kg)²

Variance=128.87270 kg²

Therefore, the variance of their weights is 128.87270 kg².

Learn more about standard deviation here:

brainly.com/question/16555520

#SPJ4

7 0

2 years ago

A newspaper reports that the population mean annual salary of a full-time college professor in a certain region is exactly $127,

Leya [2.2K]

Answer:

Option B) Fail to reject the null hypothesis that the true population mean annual salary of full-time college professors in the region is equal to $127,000.

Step-by-step explanation:

We are given the following in the question:

Population mean, μ = $127,000

Sample mean, $\bar{x}$ = $126,092

Sample size, n = 160

Alpha, α = 0.10

Sample standard deviation, σ = $8,509

First, we design the null and the alternate hypothesis

$H_{0}: \mu = 127000\text{ dollars}\\H_A: \mu \neq 127,000\text{ dollars}$

We use Two-tailed t test to perform this hypothesis.

Formula:

$t_{stat} = \displaystyle\frac{\bar{x} - \mu}{\frac{\sigma}{\sqrt{n}} }$

$t_{stat} = -1.35$

Now, $t_{critical} \text{ at 0.10 level of significance, 159 degree of freedom } = \pm 1.654$

Since,

The calculated t-statistic lies in the acceptance region, we fail to reject and accept the null hypothesis.

Option B) Fail to reject the null hypothesis that the true population mean annual salary of full-time college professors in the region is equal to $127,000.

8 0

3 years ago

Sarah had invested $800 in a savings account that paid 4.2% interest compounded annually. How much money was in the account afte

schepotkina [342]

Answer: $943.11

<u>Step-by-step explanation:</u>

Compound Interest formula is: $A=P(1+r)^t$ where

A is the Accrued amount (total earned)
P is the Principal (amount initially invested)
r is the interest Rate (convert percent to a decimal)
t is the Time (number of years)

It is given that; P = 800 r = 4.2% (0.042) t = 4

A = 800(1 + 0.042)⁴

A = 800(1.042)⁴

A = 943.106 → A = 943.11 (rounded to the nearest penny)

Sarah invested $800 for four years at an interest rate of 4.2% and accrued $943.11

5 0

3 years ago