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2 years ago

I HAVE ONE WEEK OF SCHOOL CAN SOMEONE HELP?!

Mathematics

1 answer:

ira [324]2 years ago

8 0

9514 1404 393

Answer:

1. 5 seconds

2. 4.5 seconds

Step-by-step explanation:

Both of these questions can be solved the same way. Each quadratic gives height as a function of time. You're interested in the time at which the height is zero. Factor the quadratic and find the positive value of x that makes the relevant factor be zero.

1) y = -15x(x -5)

x = 5 makes the second factor zero

The golf ball is in the air 5 seconds.

2) y = -12x(x -4.5)

x = 4.5 makes the second factor zero

The football is in the air for 4.5 seconds.

_____

<em>Additional comment</em>

The "zero product rule" tells you a product will be zero if and only if one or more of the factors is zero. When a factored quadratic (or any other polynomial) is zero, one of the factors must be zero. If the factor is of the form (ax+b), then the corresponding solution is ...

ax+b = 0 ⇒ ax = -b ⇒ x = -b/a

That is, once you have the factored form, you can write the solutions "by inspection."

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Shelly and Steve buy prepaid phone

muminat

Answer:

Steve

Step-by-step explanation:

steve is buying 200 minutes which is more than 150 minutes

Hope i helped :) :) :)

5 0

3 years ago

Starting in the 1970s, medical technology allowed babies with very low birth weight (VLBW, less than 1500 grams, about 3.3 pound

cluponka [151]

Answer:

The test statistic value using the VLBW babies as group 1 is z=-2.76±0.01 and the P-value for the test (±0.0001) is 0.0030.

Step-by-step explanation:

This is a hypothesis test for the difference between proportions.

The claim is that the proportion of persons with normal birth weight that graduates from high school is significantly greater than the proportion of persons with very low birth weight that graduates from high school.

Then, the null and alternative hypothesis are:

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

The significance level is 0.05.

The sample 1 (VLBW group), of size n1=244 has a proportion of p1=0.77049.

$p_1=X_1/n_1=188/244=0.77049$

The sample 2 (control group), of size n2=247 has a proportion of p2=0.79757.

$p_2=X_2/n_2=197/247=0.79757$

The difference between proportions is (p1-p2)=-0.02708.

$p_d=p_1-p_2=0.77049-0.79757=-0.02708$

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

$p=\dfrac{X_1+X_2}{n_1+n_2}=\dfrac{188+197}{244+247}=\dfrac{385}{491}=0.988$

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

$s_{p1-p2}=\sqrt{\dfrac{p(1-p)}{n_1}+\dfrac{p(1-p)}{n_2}}=\sqrt{\dfrac{0.988*0.012}{244}+\dfrac{0.988*0.012}{247}}\\\\\\s_{p1-p2}=\sqrt{0.00005+0.00005}=\sqrt{0.0001}=0.0098$

Then, we can calculate the z-statistic as:

$z=\dfrac{p_d-(\pi_1-\pi_2)}{s_{p1-p2}}=\dfrac{-0.02708-0}{0.0098}=\dfrac{-0.02708}{0.0098}=-2.76$

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

$P-value=P(t$

As the P-value (0.0030) is smaller than the significance level (0.05), the effect issignificant.

The null hypothesis is rejected.

There is enough evidence to support the claim that the proportion of persons with normal birth weight that graduates from high school is significantly greater than the proportion of persons with very low birth weight that graduates from high school.

3 0

3 years ago

Please help asap What is the sum of the following two polynomials?<br> (3x2 – 5x + 3) and (-x2 – 3x)

Anton [14]

(3x^2 - 5x +3) + (-2x -3x)
=3x^2-5x+3 + (6x^2)
=9x^2-5x+3

4 0

3 years ago

Read 2 more answers

The difference of twice a number and 3 is -21 translated

Westkost [7]

Answer:

2x-3=-21.

2x=-21+3.

2x=-18.

x=-18/2.

x= -9.

7 0

3 years ago

Read 2 more answers

Eights rooks are placed randomly on a chess board. What is the probability that none of the rooks can capture any of the other r

lbvjy [14]

Answer:

$4.51\times10^{-10}$

Step-by-step explanation:

There are only 2 solutions for none of the rooks can capture any of the other rooks: only if they are laid out in either of the 2 diagonal of the chess board

The number of possible combination for the rock to laid out in 8x8 (64 slots) chess board

$\frac{64 * 63 * 62 * 61 * 60 * 59 * 58 * 57}{8!} = \frac{1.78\times10^{14}}{40320} = 4426165368$ possible combination

So the probability is pretty thin

$P = 2 / 4426165368 = 4.51\times10^{-10}$

4 0

3 years ago