Help plss (100pts) Direct variation

A basketball team plays 82 games each year. How many games will the team play in 25 years?

exis [7]

2050 games will be played in 25 yrs

6 0

2 years ago

The following data lists the ages of a random selection of actresses when they won an award in the category of Best Actress, al

Valentin [98]

Answer:

a) $p_v =P(t_{(9)}$

The p value is higher than the significance level given 0.01, so then we can conclude that we FAIL to reject the null hypothesis. And we can say that the true difference for Best Actresses is not significantly lower than the mean for Best Actors at 1% of significance.

b) The 99% confidence interval would be given by (-21.469;2.069)

c) We got the same conclusion as part a, sicne the confidence interval contains the value 0, we FAIL to reject the null hypothesis that the difference between the two

Step-by-step explanation:

Part a

Let put some notation

x=actor's age , y = actress's age

x: 58 41 36 36 34 33 48 37 37 43

y: 26 27 34 26 35 29 23 42 30 34

The system of hypothesis for this case are:

Null hypothesis: $\mu_y- \mu_x \geq 0$

Alternative hypothesis: $\mu_y -\mu_x$

The first step is calculate the difference $d_i=y_i-x_i$ and we obtain this:

d: -32, -14, -2, -10, 1, -4, -25, 5, -7, -9

The second step is calculate the mean difference

$\bar d= \frac{\sum_{i=1}^n d_i}{n}= -9.7$

The third step would be calculate the standard deviation for the differences, and we got:

$s_d =\frac{\sum_{i=1}^n (d_i -\bar d)^2}{n-1} =11.451$

The 4 step is calculate the statistic given by :

$t=\frac{\bar d -0}{\frac{s_d}{\sqrt{n}}}=\frac{-9.7 -0}{\frac{11.451}{\sqrt{10}}}=-2.679$

The next step is calculate the degrees of freedom given by:

$df=n-1=10-1=9$

Now we can calculate the p value, since we have a left tailed test the p value is given by:

$p_v =P(t_{(9)}$

The p value is higher than the significance level given 0.01, so then we can conclude that we FAIL to reject the null hypothesis. And we can say that the true difference for Best Actresses is not significantly lower than the mean for Best Actors at 1% of significance.

Part b

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

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".

The confidence interval for the mean is given by the following formula:

$\bar d \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.005,9)".And we see that $t_{\alpha/2}=3.25$

Now we have everything in order to replace into formula (1):

$-9.7-3.25\frac{11.451}{\sqrt{10}}=-21.469$

$-9.7+3.25\frac{11.451}{\sqrt{10}}=2.069$

So on this case the 99% confidence interval would be given by (-21.469;2.069)

Part c

We got the same conclusion as part a, sicne the confidence interval contains the value 0, we FAIL to reject the null hypothesis that the difference between the two means is 0.

8 0

3 years ago

A scientist need 10 L of a 20% acid solution for an experiment where she had only a 5% solution and a 40% solution to the neares

andrezito [222]

Answer:

Amount of 5% solution = 5.7 Litres

Amount of 40% solution = 4.3 Litres

Step-by-step explanation:

First, of all, let x be the amount of 5% solution used

Since, the scientist needs 10 L of solution, then;

Let 10 - x be the amount of 40% solution used

Now, we are told that she needs 10 L of a 20% acid solution.

This means that;

5%x + 40%(10 - x) = 20%(10).

Simplifying this gives;

0.05x + 0.40(10 - x) = 0.20 × 10

Expanding the bracket gives;

0.05x + 4 - 0.4x = 2

0.4x - 0.05x = 4 - 2

0.35x = 2

x = 2/0.35

x ≈ 5.7 litres

Thus, she will need to mix 5.7 liters of the 5% solution.

Since 10 - x be the amount of 40% solution used , then;

the amount of 40% solution = 10 - 5.7 = 4.3 litres

4 0

3 years ago

WILL GIVE BRAINLIEST, THANKS, AND 5 STARS! PLEASE HELP ME!

Bogdan [553]

Answer:

-4 and 4

Step-by-step explanation:

Method 1

Apply Difference of Two Squares Formula: $a^2-b^2=(a+b)(a-b)$

Given $x^2-16=0$

Rewrite 16 as 4²

Therefore, $a^2=x^2$ and $b^2=4^2$

$\implies a = \sqrt{x^2}=x$

$\implies b=\sqrt{4^2} =4$

$\implies x^2-16^2=(x+4)(x-4)$

$\implies (x+4)(x-4)=0$

$\implies (x+4)=0 \implies x=-4$

$\implies (x-4)=0 \implies x=4$

Method 2

Given equation:

$x^2-16=0$

Add 16 to both sides:

$\implies x^2-16+16=0 + 16$

$\implies x^2=16$

Square root both sides:

$\implies \sqrt{x^2}=\sqrt{16}$

$\implies x=\pm4$

Therefore, x = -4, x = 4

6 0

2 years ago

Unit rates can be helpful with creating a ratio table and plotting the equivalent ratios on a coordinate plane. Explain why. PLE

uysha [10]

Answer:

Unit rate is often a useful means for comparing ratios and their associated rates when measured in different units. The unit rate allows us to compare varying sizes of quantities by examining the number of units of one quantity per one unit of the second quantity. This value of the ratio is the unit rate.

3 0

2 years ago