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3 years ago

If y varies directly with x and y = 5 when x = 4, find the value of y when x = -8.

Mathematics

1 answer:

lilavasa [31]3 years ago

8 0

Answer:

-10

Step-by-step explanation:

y= kx

or, k= y/x

or, k = 5/4

k = 1.25

y= kx = 1.25 × (-8) = -10

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So what you need to do is find the volume and divide it by 2.

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2 years ago

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You need to solve a system of equations. You decide to use the elimination method. Which of these is not allowed? 3x-2y=7 equati

svetlana [45]

Answer:

x = 31/9 and y = 5/3

Step-by-step explanation:

It is given that,

3x - 2y = 7 -----(1)

3x + 4y = 17 ----(2)

To find the solution by elimination method

Step 1: Subtract eq(2) from eq(1)

3x - 2y = 7 -----(1)

3x + 4y = 17 ----(2)

0 - 6y = -10

6y = 10

y = 10/6 = 5/3

Step 2: Substitute the value of y in eq (1)

3x - 2y = 7 -----(1)

3x - 2*(5/3) = 7

3x = 7 + 10/3

3x = 31/3

x = 31/9

Therefore x = 31/9 and y = 5/3

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3 years ago

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The average waist size for teenage males is 29 inches with astandard deviation of 2 inches. If waist sizes are normallydistribut

choli [55]

Answer:

The z-score of a teenage with waist size 33 inch is 2

Step-by-step explanation:

Mathematically, the z-score can be calculated using the formula;

z-score = (x- mean)/SD

where mean = 29 inches , SD = 2 inches and x = 33 inch

Plugging these values, we have

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3 years ago

(01.03 MC) Which of the following is a step in simplifying the expression (Xy^4/x^-5y^5)^3

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$\displaystyle\tt\left(\frac{xy^4}{x^{-5}y^5}\right)^{-3} =\frac{x^{-3}y^{4\cdot(-3)}}{x^{-5\cdot(-3)}y^{5\cdot(-3)}}=\boxed{\tt\frac{x^{-3}y^{-12}}{x^{15}y^{-15}}}$

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3 years ago

Tennis elbow is thought to be aggravated by the impact experienced when hitting the ball. The article "Forces on the Hand in the

Gnoma [55]

Answer:

Step-by-step explanation:

Hello!

The objective is to study whether there is a greater force after impacting on one- handed backhand drive in advanced tennis players than in intermediate tennis players.

Sample 1: Advanced tennis players

X₁: Force (N) on the hand just after impact on a one- handed backhand drive for an advanced tennis player.

n₁= 6

X[bar]₁= 40.29 N

S₁= 11.29

Sample 2: Intermediate players

X₂: Force (N) on the hand just after impact on a one- handed backhand drive for an intermediate tennis player.

n₂= 8

X[bar]₂= 21.40

S₂= 8.30

Assuming that both variables have a normal distribution and both population variances are equal, to compare these two populations is best to do so trough their population means using a t-test for independent samples.

If the force is greater for the advanced players than for the intermediate players, then you'd expect the population mean for the advanced players to be greater than the population mean for the intermediate players:

H₀: μ₁ ≤ μ₂

H₁: μ₁ > μ₂

α: 0.05

$t= \frac{(X_[bar]_1-X[bar]_2)-(Mu_1-Mu_2)}{Sa\sqrt{\frac{1}{n_1} +\frac{1}{n_2} } } ~~t_{n_1+n_2-2}$

$Sa= \sqrt{\frac{(n_1-1)S_1^2+(n_2-1)S_2^2}{n_1+n_2-2} } = \sqrt{\frac{5*127.51+7*68.92}{6+8-2} }= 9.66$

$t_{H_0}= \frac{(40.29-21.40)-0}{9.66\sqrt{\frac{1}{6} +\frac{1}{8} } } = 3.62$

Using the p-value approach, the decision rule is

If p-value ≤ α, reject the null hypothesis

If p-value > α, do not reject the null hypothesis

The p-value for this test is 0.00024, it is less than the level of significance, so the decision is to reject the null hypothesis.

This means that at a 5% significance level you can conclude that the average force experienced on the hand after a one-handed backhand drive for advanced players is greater than the average force experienced on the hand after a one-handed backhand drive for intermediate players.

I hope this helps!

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3 years ago