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3 years ago

X^2-2y/y when x=20 and y=x/2

Mathematics

2 answers:

DerKrebs [107]3 years ago

4 0

Answer:

I believe its 398

Step-by-step explanation:

vagabundo [1.1K]3 years ago

3 0

Answer:

398

Step-by-step explanation:

x^2=400

substitute for y, 2y/y=(2*x/2)/(x/2)=x/(x/2)=x*(2/x)=2

400-2=398

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One of your peers claims that boys do better in math classes than girls. Together you run two independent simple random samples

JulijaS [17]

Answer:

Step-by-step explanation:

Hello!

To test if boys are better in math classes than girls two random samples were taken:

Sample 1

X₁: score of a boy in calculus

n₁= 15

X[bar]₁= 82.3%

S₁= 5.6%

Sample 2

X₂: Score in the calculus of a girl

n₂= 12

X[bar]₂= 81.2%

S₂= 6.7%

To estimate per CI the difference between the mean percentage that boys obtained in calculus and the mean percentage that girls obtained in calculus, you need that both variables of interest come from normal populations.

To be able to use a pooled variance t-test you have to also assume that the population variances, although unknown, are equal.

Then you can calculate the interval as:

[(X[bar]_1-X[bar_2) ± $t_{n_1+n_2-2;1-\alpha /2}$ * $Sa*\sqrt{\frac{1}{n_1} +\frac{1}{n_2} }$ ]

$Sa= \sqrt{\frac{(n_1-1)S^2_1+(n_2-1)S^2_2}{n_1+n_2-2} } = \sqrt{\frac{14*(5.6^2)+11*(6.7^2)}{15+12-2} }= 6.108= 6.11$

$t_{n_1+n_2-2;1-\alpha /2}= t_{15+12-2;1-0.05}= t_{25;0.95}= 1.708$

[(82.3-81.2) ± 1.708* (6.11* $\sqrt{\frac{1}{15}+\frac{1}{12} }$ ]

[-2.94; 5.14]

Using a 90% confidence level you'd expect the interval [-2.94; 5.14] to contain the true value of the difference between the average percentage obtained in calculus by boys and the average percentage obtained in calculus by girls.

I hope this helps!

3 0

3 years ago

23. The price of jeans was reduced $6 per week

ohaa [14]

Answer:

$42

Step-by-step explanation:

Every week, the price of jeans reduced by $6.

The total value of price reduction over the 7-week period can be calculated as the product of price reduction per week and the number of weeks. Thus,

Total price reduction = price reduction per week x number of weeks

= $6 x 7

=$ 42

4 0

3 years ago

What is the equation of the function y=5/x translated 4 units to the left and 3 units up?

Elenna [48]

12 is your answer hope this helps

3 0

3 years ago

Marley solve 345 -176 and then checked her work which pair of number sentences did she u

polet [3.4K]

Answer:

Could you finish the question???

Step-by-step explanation:

8 0

3 years ago

Cynthia Besch wants to buy a rug for a room that is 19 ft wide and 32 ft long. She wants to leave a uniform strip of floor aroun

Rainbow [258]

Answer:

The rug should be 15 ft wide and 28 ft long.

Step-by-step explanation:

I have attached a figure that represents the situation.

The the rug is $l$ by $h$ , the width of the strip of floor is $w$ .

We are told that Cynthia can only afford 420 square feet of carpeting; therefore, it must be that

$l*h=420$ <em>(this says the area of the rug must be 420 square feet)</em>

From the figure we see that

$l= 32-2w$

$h=19-2w$

Therefore,

$l*h=420\\\\(32-2w)(19-2w)=420$

We expand this equation and get:

$4w^2-102w+608=420\\\\4w^2-102w+188=0$

using the quadratic equation we get two solutions:

$w=2\\w=23.5$

since the second solution, namely $w=23.5$ , is larger than one of the dimensions of the room (is greater than 19 ft) it cannot be the width of the strip; therefore, we take $w=2$ to be our solution.

Now we find the dimensions of the rug:

$l=32-2(2)=28\\\\h=19-2(2)=15$

The rug is 15 ft wide and 28 ft long.

8 0

3 years ago