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3 years ago

A(-1,-5), B(5,-2) and C(1, 1).

Mathematics

1 answer:

VLD [36.1K]3 years ago

6 0

Answer:

D(-3, -1)

Step-by-step explanation:

The given coordinates are;

A(-1, -5), B(5, -2) and (1, 1)

The coordinates and the coordinates of the point D form a trapezium

The parallel sides of the trapezium ABCD = AB and DC

The angle ∠BAD = 90°

The coordinates of the point D = Required

Let (x, y) represent the x and y-coordinates of the point D, by the given information, we get;

The slope of the line DC = The slope of the line AB

The slope of AB = (-2 - (-5))/(5 - (-1)) = 3/6 = 1/2

∴ The slope of CD, m = 1/2

From the point C(1, 1),the equation of the line CD is therefore;

y - 1 = (1/2)·(x - 1)

∴ y = x/2 - (1/2) + 1 = x/2 + 1/2

y = x/2 + 1/2

Given that ∠BAD is 90°, therefore, AD is perpendicular to DC and we have;

The slope of AD = -1/m

∴ The slope of AD = -1/(1/2) = -2

From the point A(-1, -5), the equation of the line AD is therefore;

y - (-5) = -2·(x - (-1))

y = -2·x - 2 - 5 = -2·x - 7

y = -2·x - 7

Equating both (simultaneous) values of y to find the value of x gives;

y = y, therefore;

x/2 + 1/2 = -2·x - 7

x/2 + 2·x = 5·x/2 = -7 - (1/2) = -15/2

∴ 5·x/2 = -15/2

x = (-15/2) × (2/5) = -3

x = -3

From y = -2·x - 7, and x = -3, we get;

y = -2 × (-3) - 7 = 6 - 7 = -1

The coordinates of the point D(x, y) = (-3, -1).

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The Salk polio vaccine experiment in 1954 focused on the effectiveness of the vaccine in combating paralytic polio. Because it w

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Answer:

Step-by-step explanation:

Hello!

The variables of interest are:

X₁: Number of cases of polio observed in kids that received the placebo vaccine.

n₁= 201299 total children studied

x₁= 110 cases observed

X₂: Number of cases of polio observed in kids that received the experimental vaccine.

n₂= 200745 total children studied

x₂= 33 cases observed

These two variables have a binomial distribution. The parameters of interest, the ones to compare, are the population proportions: p₁ vs p₂

You have to test if the population proportions of children who contracted polio in both groups are different: p₂ ≠ p₁

H₀: p₂ = p₁

H₁: p₂ ≠ p₁

α: 0.05

$Z= \frac{(p'_2-p'_1)-(p_2-p_1)}{\sqrt{p'[\frac{1}{n_1} +\frac{1}{n_2} ]} }$

Sample proportion placebo p'₁= x₁/n₁= 110/201299= 0.0005

Sample proportion vaccine p'₂= x₂/n₂= 33/200745= 0.0002

Pooled sample proportion p'= (x₁+x₂)/(n₁+n₂)= (110+33)/(201299+200745)= 0.0004

$Z_{H_0}= \frac{(0.0002-0.0005)-0}{\sqrt{0.0004[\frac{1}{201299} +\frac{1}{200745} ]} }= -4.76$

This test is two-tailed, using the critical value approach, you have to determine two critical values:

$Z_{\alpha/2}= Z_{0.025}= -1.96$

$Z_{1-\alpha /2}= Z_{0.975}= 1.96$

Then if $Z_{H_0}$ ≤ -1.96 or if $Z_{H_0}$ ≥ 1.96, the decision is to reject the null hypothesis.

If -1.96 < $Z_{H_0}$ < 1.96, the decision is to not reject the null hypothesis.

⇒ $Z_{H_0}$ = -4.76, the decision is to reject the null hypothesis.

H₀: p₂ = p₁

H₁: p₂ ≠ p₁

α: 0.01

$Z= \frac{(p'_2-p'_1)-(p_2-p_1)}{\sqrt{p'[\frac{1}{n_1} +\frac{1}{n_2} ]} }$

The value of $Z_{H_0}$ = -4.76 doesn't change, since we are working with the same samples.

The only thing that changes alongside with the level of significance is the rejection region:

$Z_{\alpha /2}= Z_{0.005}= -2.576$

$Z_{1-\alpha /2}= Z_{0.995}= 2.576$

Then if $Z_{H_0}$ ≤ -2.576or if $Z_{H_0}$ ≥ 2.576, the decision is to reject the null hypothesis.

If -2.576< $Z_{H_0}$ < 2.576, the decision is to not reject the null hypothesis.

⇒ $Z_{H_0}$ = -4.76, the decision is to reject the null hypothesis.

Remember the level of significance (probability of committing type I error) is the probability of rejecting a true null hypothesis. This means that the smaller this value is, the fewer chances you have of discarding the true null hypothesis. But as you know, you cannot just reduce this value to zero because, the smaller α is, the bigger β (probability of committing type II error) becomes.

Rejecting the null hypothesis using different values of α means that there is a high chance that you reached a correct decision (rejecting a false null hypothesis)

I hope this helps!

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4 years ago

Margie's car can go 32 miles on a gallon of gas, and gas currently costs $4 per gallon. How many miles can Margie drive on $20 w

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32 miles = 4 dollars per gallon.

32 * 5 = 160

160 miles on 20 dollars of gas.

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3 years ago

B) If A (-3, 2) is translated by

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Answer:

A'(-6,4)

Step-by-step explanation:

A transformation of (x, y) → (x-3, y + 2) means:

x coordinate gets translated 3 units left [we subtract 3 from original x coordinate]
y coordinate gets translated 2 units up [we add 2 to original y coordinate]

The original x coordinate is -3 so we subtract 3 from it to get:

New x = -3 -3 = -6

The original y coordinate is 2 so we add 2 to get:

New y = 2 + 2 = 4

So A' is

A'(-6,4)

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3 years ago

On average, Scott drinks ½ of a 6-ounce glass of water in ⅔ hour. How much water does he drink in an hour?

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3 years ago

Sadie is 3 years older than Kareem, and Kareem is twice as old as Nadra. The sum of their ages is 33.

Dima020 [189]

Answer:

Step 1-Write an equation, letting x represent Kareem’s age:

(x + 3) + x + 2 x = 33

Step 2-Solve the equation:

(x + 3) + x + 2 x = 33. 3 + 4 x = 33. 4 x = 30. x = 7 1/2.

Step 3-Sadie is 10 1/2, Kareem is 7 1/2, and Nadra is 3 3/4.

Which corrects the student’s first error?

1. In Step 1, the student should have used One-half x to represent Nadra’s age, and written the equation (x + 3) + x +1/2x = 33.

2. In Step 2, the student should have added 3 on both sides of the equation to find a solution of x = 9.

3. In Step 3, the solution represents Sadie’s age. Therefore, Sadie is 7 1/2, Kareem is 4 1/2, and Nadra is 2 1/4.

4. In Step 3, Nadra’s age is the difference between 33 and Sadie’s and Kareem’s ages, so Nadra is 15.

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2 years ago