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2 years ago

How can you decide which operation to use to solve a problem?

Mathematics

1 answer:

almond37 [142]2 years ago

7 0

Answer:

it you're asking for like an equation like "4x +3 = 15 " then you do the opposite of what the equation is doing. Basically undoing the problem to get back to the roots of it. like for the example i provided you would subtract 3 from both sides, because it was added originally. then you would divide both sides by 4 because originally you were multiplying.

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In triangle KLM, if K is congruent to L, KL = 9x - 40, LM = 7x - 37, & KM = 3x + 23, find x & the measure of each angle.

Dennis_Churaev [7]

Answer: x = 15, ∠K = 45.7°, ∠L = 45.7°, ∠M = 88.6°

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

Since ∠K ≅ ∠L, then ΔKLM is an isoceles triangle with base KL

KM ≅ LM

3x + 23 = 7x - 37

23 = 4x - 37

60 = 4x

15 = x

KM = LM = 3x + 23

= 3(15) + 23

= 45 + 23

= 68

KL = 9x - 40

= 9(15) - 40

= 135 - 40

= 95

Next, draw a perpendicular bisector KN from K to KL. Thus, N is the midpoint of KL and ΔMNL is a right triangle.

Since N is the midpoint of KL and KL = 95, then NL = 47.5
Since ∠N is 90°, then NL is adjacent to ∠l and ML is the hypotenuse

Use trig to solve for ∠L (which equals ∠K):

cos ∠L = $\frac{adjacent}{hypotenuse}$

cos ∠L = $\frac{47.5}{68}$

∠L = cos⁻¹ $(\frac{47.5}{68})$

∠L = 45.7

Triangle sum Theorem:

∠K + ∠L + ∠M = 180°

45.7 + 45.7 + ∠M = 180

91.4 + ∠M = 180

∠M = 88.6

7 0

3 years ago

What is the gcf of 3xy and 42xy

nignag [31]

Since 3 divides 42, 3xy itself is the greatest common factor of 3xy and 42xy.

Answer: 3xy

7 0

3 years ago

What is the chemical formula for the molecule modeled?

adelina 88 [10]

The correct answer is A

8 0

3 years ago

Read 2 more answers

23. A certain type of gasoline is supposed to have a mean octane rating of at least 90. Suppose measurements are taken on of 5 r

Nostrana [21]

Answer:

a) $p_v =P(Z$

b) Since $p_v$ we can reject the null hypothesis at the significance level given. So based on this we can commit type of Error I.

Because Type I error " is the rejection of a true null hypothesis".

c) $P(\bar X >90)=1-P(Z$

$1-P(Z$

d) For this case we need a z score that accumulates 0.02 of the area on the right tail and 0.98 on the left tail and this value is z=2.054

And we can use this formula:

$2.054=\frac{90-89}{\frac{0.8}{\sqrt{n}}}$

And if we solve for n we got:

$n = (\frac{2.054 *0.8}{1})^2=2.7 \approx 3$

Step-by-step explanation:

Previous concepts and data given

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".

We can calculate the sample mean and deviation with the following formulas:

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

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

$\bar X=88.96$ represent the sample mean

$s=1.011$ represent the sample standard deviation

n=5 represent the sample selected

$\alpha$ significance level

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the mean is less than 90, the system of hypothesis would be:

Null hypothesis: $\mu \geq 90$

Alternative hypothesis: $\mu < 90$

If we analyze the size for the sample is < 30 and we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}$ (1)

z-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:

$z=\frac{88.96-90}{\frac{0.8}{\sqrt{5}}}=-2.907$