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3 years ago

10

Volunteers were 3/4 finished with the walkathon when they reached the 4 1/2 kilometer mark. How many kilometers was the walkatho

n

1 answer:

den301095 [7]3 years ago

5 0

5 I think, cause if your 3/4 ways done you need to walk 1/2 more kilometers to be finished... So if you add 1/2 to 41/2 it equals 5

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I need help on #10. very confused

RideAnS [48]

Step-by-step explanation:

$\displaystyle f'(x) = \lim_{h \to 0} \dfrac{f(x + h) - f(x)}{h}$

$\:\:\:\:\:\displaystyle = \lim_{h \to 0} \dfrac{(x+h)^2 -7 -(x^2 - 7)}{h}$

$\:\:\:\:\: \displaystyle= \lim_{h \to 0} \dfrac{(x^2 +2hx + h^2 -7) - (x^2 -7)}{h}$

$\:\:\:\:\: \displaystyle= \lim_{h \to 0} \dfrac{2hx + h^2}{h}$

$\:\:\:\:\: \displaystyle= \lim_{h \to 0} (2x +h)$

$\:\:\:\:\: \displaystyle= 2x$

3 0

3 years ago

AT&T would like to test the hypothesis that the proportion of 18- to 34-year-old Americans that own a cell phone is less tha

Vera_Pavlovna [14]

Answer:

The null and alternative hypothesis can be written as:

$H_0: \pi_1-\pi_2=0\\\\H_a:\pi_1-\pi_2< 0$

Step-by-step explanation:

This is a hypothesis test for the difference between proportions.

The claim is that the proportion of 18- to 34-year-old Americans that own a cell phone is less than the proportion of 35- to 49-year-old Americans.

This claim will be reflected in the alternnative hypothesis, that will state that the population proportion 1 (18 to 34) is significantly smaller than the population proportion 2 (35 to 49).

On the contrary, the null hypothesis will state that the population proportion 1 is ot significantly smaller than the population proportion 2.

Then, the null and alternative hypothesis can be written as:

$H_0: \pi_1-\pi_2=0\\\\H_a:\pi_1-\pi_2< 0$

The significance level is assumed to be 0.05.

The sample 1, of size n1=200 has a proportion of p1=0.63.

$p_1=X_1/n_1=126/200=0.63$

The sample 2, of size n2=175 has a proportion of p2=0.68.

$p_2=X_2/n_2=119/175=0.68$

The difference between proportions is (p1-p2)=-0.05.

$p_d=p_1-p_2=0.63-0.68=-0.05$

The pooled proportion, needed to calculate the standard error, is:

$p=\dfrac{X_1+X_2}{n_1+n_2}=\dfrac{126+119}{200+175}=\dfrac{245}{375}=0.653$

The estimated standard error of the difference between means is computed using the formula:

$s_{p1-p2}=\sqrt{\dfrac{p(1-p)}{n_1}+\dfrac{p(1-p)}{n_2}}=\sqrt{\dfrac{0.653*0.347}{200}+\dfrac{0.653*0.347}{175}}\\\\\\s_{p1-p2}=\sqrt{0.001132+0.001294}=\sqrt{0.002427}=0.049$

Then, we can calculate the z-statistic as:

$z=\dfrac{p_d-(\pi_1-\pi_2)}{s_{p1-p2}}=\dfrac{-0.05-0}{0.049}=\dfrac{-0.05}{0.049}=-1.01$

This test is a left-tailed test, so the P-value for this test is calculated as (using a z-table):

$\text{P-value}=P(z$

As the P-value (0.1554) is bigger than the significance level (0.05), the effect is not significant.

The null hypothesis failed to be rejected.

There is not enough evidence to support the claim that the proportion of 18- to 34-year-old Americans that own a cell phone is less than the proportion of 35- to 49-year-old Americans.

5 0

3 years ago

Answer all these guestions corectly and i will be so thankfull and will mark u brainiest.

Lana71 [14]

1) A = π r² = 22/7 x 10² = 314.28 in²

2)A = π r² = 22/7 x 9² = 254.57 mm²

3) radius = 1/2 diameter
r = 1/2 x 3 = 1.5 in

A = π r² = 22/7 x 1.5² = 7.07 in²

4)A = π r² = 22/7 x 14² =616 cm²

5) radius = 1/2 diameter
r = 1/2 x 1.5 = 0.75 ft

A = π r² = 22/7 x 0.75² = 1.76 ft²

4 0

3 years ago

Read 2 more answers

F(x) = 3x +2 is it linear quadratic exponential

nadya68 [22]

I think you are looking for the value of x
3x+2
-2

3x
X=3

5 0

3 years ago

(20pts) Prove that the product of any two odd numbers is always odd. Make sure to explain your proof

kozerog [31]

Answer:

See below (I hope this helps!)

Step-by-step explanation:

Because odd numbers are always 1 greater than even numbers, we can call the two odd numbers x + 1 and y + 1 where x and y are even integers. Multiplying the two gives us:

(x + 1) * (y + 1)

= x * y + x * 1 + 1 * y + 1 * 1

= xy + x + y + 1

We know that x * y will be even because x and y are also even and the sum of two even numbers will be even, and we also know that x and y are even and that 1 is odd. Since the sum of even and odd numbers is always odd, the product of any two numbers is always odd.

*NOTE: I put a limitation on x and y in my proof (the limitation was that x and y must be EVEN integers) but you don't have to do that, you could make the odd integers 2x + 1 and 2y + 1 where x and y could be any integer from the set Z like mirai123 did. I simply gave this proof because it was the first thing that came to mind. While mirai123's proof and mine are different, they are still both correct.

5 0

3 years ago

Read 2 more answers