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3 years ago

The length of a swimming poollane

Mathematics

1 answer:

Hunter-Best [27]3 years ago

8 0

Answer:

x²+5x - 150 = 0

Step-by-step explanation:

Let the length be y and width be x

If the length of a swimming pool is 10 more than 2 times the width, then;

y = 2x+10 ...1

Since the Area is 300m²

A = xy

300 = xy .... 2

Substitute 1 into 2

300 = x(2x+10)

300 = 2x²+10x

Rearrange

2x²+10x - 300 = 0

Divide through by 2

x²+5x - 150 = 0

This gives the required quadratic expression

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Find the measurement of an interior angle of a regular decagon (10-sided figure).

natita [175]

Answer:

144°

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

Geometry

Sum of Angles: 180(n - 2)

Step-by-step explanation:

Step 1: Define

Number of sides n = 10

Step 2: Find

Substitute: 180(10 - 2)
Subtract: 180(8)
Multiply: 1440°

Step 3: Find 1 angle

We have 10 sides.

Divide: 1440/10 = 144

8 0

3 years ago

Help worth 50 points!

Darina [25.2K]

Answer:

x>-2

Step-by-step explanation:

-9x-15<3

+15<+15 add 15 to both sides

_________

-9x<18

÷-9 <÷-9 divide both sides by -9, switch inequality _________ symbol when dividing by negative number.

x>-2 Answer

_________

8 0

3 years ago

The health of the bear population in a park is monitored by periodic measurements taken from anesthetized bears. A sample of the

Vikki [24]

Answer:

$182.167-2.03\frac{114.05}{\sqrt{36}}=143.580$

$182.167+2.03\frac{114.05}{\sqrt{36}}=220.754$

So on this case the 95% confidence interval would be given by (143.580;220.754)

Step-by-step explanation:

Assuming the following dataset:

77, 349,417,349, 167 , 225, 265, 360,205

145,335,40,139, 177,108, 163, 202, 22

123,439, 125,135, 86,43, 217,49, 156

119,178, 151, 61, 350, 312, 91, 89,89

We can calculate the sample mean with the followinf formula:

$\bar X = \frac{\sum_{i=1}^n X_i}{n}= 182.167$

And the sample deviation with:

$s = \sqrt{\frac{\sum_{i=1}^n (X_i-\bar X)^2}{n-1}}=114.05$

The sample size on this case is n =36.

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$\bar X=182.167$ represent the sample mean

$\mu$ population mean (variable of interest)

s=114.05 represent the sample standard deviation

n=36 represent the sample size

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

The point estimate of the population mean is $\hat \mu = \bar X =182.167$

In order to calculate the critical value $t_{\alpha/2}$ we need to find first the degrees of freedom, given by:

$df=n-1=36-1=35$

Since the Confidence is 0.95 or 95%, the value of $\alpha=0.05$ and $\alpha/2 =0.025$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,35)".And we see that $t_{\alpha/2}=2.03$