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3 years ago

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A builder was building a fence. In the morning, he worked for 2/5 of an hour. In the afternoon, he worked for 9/10 of an hour. H

ow many times as long as in the morning did he work in the afternoon? Write a division equation to represent this situation, then answer the question. Show your reasoning. If you get stuck, you can draw a diagram.

1 answer:

guajiro [1.7K]3 years ago

3 0

Answer:believe it’s 12

Step-by-step explanation:

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Heeeeeeeeeeeeeeeeeeeeeeeelpppppppppppp

padilas [110]

Answer:

Slope = -⁵/3

Step-by-step explanation:

See the attachment below. In the attachment, the green line represents the the rise while the red line represents the run of the line.

The slope = rise/run

Rise = 5

Run = 3

Slope = -(5/3)

Slope = -⁵/3 (the slope would be negative because the line slants downwards from your left to the right)

4 0

3 years ago

What are the solutions of x^2-2x+5=0

sweet [91]

The solution of $x^{2}-2 x+5=0$ are 1 + 2i and 1 – 2i

<u>Solution:</u>

Given, equation is $x^{2}-2 x+5=0$

We have to find the roots of the given quadratic equation

Now, let us use the quadratic formula

$x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a}$ --- (1)

<em><u>Let us determine the nature of roots:</u></em>

Here in $x^{2}-2 x+5=0$ a = 1 ; b = -2 ; c = 5

$b^2 - 4ac = 2^2 - 4(1)(5) = 4 - 20 = -16$

Since $b^2 - 4ac < 0$ , the roots obtained will be complex conjugates.

Now plug in values in eqn 1, we get,

$x=\frac{-(-2) \pm \sqrt{(-2)^{2}-4 \times 1 \times 5}}{2 \times 1}$

On solving we get,

$x=\frac{2 \pm \sqrt{4-20}}{2}$

$x=\frac{2 \pm \sqrt{-16}}{2}$

$x=\frac{2 \pm \sqrt{16} \times \sqrt{-1}}{2}$

we know that square root of -1 is "i" which is a complex number

$\begin{array}{l}{\mathrm{x}=\frac{2 \pm 4 i}{2}} \\\\ {\mathrm{x}=1 \pm 2 i}\end{array}$

Hence, the roots of the given quadratic equation are 1 + 2i and 1 – 2i

6 0

3 years ago

. A high-speed maglev train in Shanghai can

tresset_1 [31]

The speed of Maglev train is 267 miles per hour.

Step-by-step explanation:

Given,

Speed of Maglev train = 430 kilometers per hour

We know that;

1 kilometer = 0.62 miles

Therefore,

430 kilometers = 0.62*430

430 kilometers = 266.6 miles

Rounding off to nearest whole number

430 kilometers = 267 miles

The speed of Maglev train is 267 miles per hour.

Keywords: Speed, conversion

Learn more about conversion at:

#LearnwithBrainly

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3 years ago

It is claimed that automobiles are driven on average more than 20,000 kilometers per year. To test this claim, 100 randomly sele

kow [346]

Answer:

$t=\frac{23500-20000}{\frac{3900}{\sqrt{100}}}=8.974$

$p_v =P(t_{99}>8.974)=9.43x10^{-15}$

If we compare the p value and the significance level given for example $\alpha=0.05$ we see that $p_v$ so we can conclude that we to reject the null hypothesis, and the actual mean is significantly higher than 20000.

Step-by-step explanation:

1) Data given and notation

$\bar X=23500$ represent the sample mean

$s=3900$ represent the sample standard deviation

$n=100$ sample size

$\mu_o =2000$ represent the value that we want to test

$\alpha$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to determine if the true mean is higher than 20000, the system of hypothesis would be:

Null hypothesis: $\mu \leq 2000$

Alternative hypothesis: $\mu > 2000$

We don't know the population deviation, so for this case is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}$ (1)

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$t=\frac{23500-20000}{\frac{3900}{\sqrt{100}}}=8.974$

Calculate the P-value

First we need to calculate the degrees of freedom given by:

$df=n-1=100-1=99$

Since is a one-side upper test the p value would be:

$p_v =P(t_{99}>8.974)=9.43x10^{-15}$

Conclusion

If we compare the p value and the significance level given for example $\alpha=0.05$ we see that $p_v$ so we can conclude that we to reject the null hypothesis, and the actual mean is significantly higher than 20000.

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3 years ago

I’ll give brainly pls help me ☹️!!!

Lera25 [3.4K]

Answer:

728000 mosquitoes

Step-by-step explanation:

In attachment

Please giv brainliest, thanks!

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3 years ago