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3 years ago

A projectile is thrown upward so that its distance above the ground after t seconds is h = -16t2 + 440t.

Mathematics

1 answer:

ladessa [460]3 years ago

5 0

Answer:

14 s

Step-by-step explanation:

We notice that the expression that shows the distance above ground as a function of time, is in fact a quadratic expression (parabola) with negative leading coefficient (-16). this means that the graph of the projectile's distance from the ground is a parabola with branches pointing down, and therefore must have a maximum value at its vertex.

We can then used the formula for finding the horizontal position of the vertex in a quadratic function of the general form $y=ax^2+bx+c$ :

$x_{vertex}=-\frac{b}{2a}$

In our polynomial $h=-16\,t^2+440\,t$ , the horizontal variable is the time (t), the value of $a$ is "-16", and $b$ is "440". Therefore, the time (horizontal variable) at which the projectile reaches the maximum height is:

$t_{vertex}=-\frac{440}{2\,(-16)} \\t_{vertex}=\frac{-440}{-32} \\t_{vertex}=13.75 \,seconds$

So we can round this answer to the nearest integer giving us about 14 seconds.

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At track practice,Sheila worked on the long jump. Her first jump measured 3 yards, 2 feet, 8 inches. Her second jump measured 2

jolli1 [7]

The length is 19.5 feet. this is because when you add the yards, it equals 15 feet. Next, add 1 + 2 feet from the first and second jump. 10+8 inches equal 1.5 feet. Next, add 15 feet+3 feet+1.5 feet to get 19.5 feet.

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3 years ago

Harry needs to build a fence around his garden, but first he must figure out the dimensions of his garden. The length of his rec

Lana71 [14]

First, we know L and W are the same number. The in the end the Length is 6 more, therefore we add 6. The equations begins as so
2x+6=27
-6
2x=21
/2
x=10.5
+6
Therefore the Width =10.5 M
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6 0

3 years ago

A report on consumer financial literacy summarized data from a representative sample of 1,664 adult Americans. Based on data fro

daser333 [38]

Answer:

a. The 95% confidence interval for the proportion of all adult Americans who would give themselves a grade of A or B on their financial knowledge of personal finance is (0.54, 0.588). This means that we are 95% sure that the true proportion of all adult Americans who would give themselves a grade of A or B on their financial knowledge of personal finance is between these two bounds.

b. Because this confidence interval is entirely above 0.5, the interval is consistent with the statement that a majority of adult Americans would give themselves a grade of A or B.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

Sample of 1,664 adult Americans, 939 people in the sample would have given themselves a grade of A or B in personal finance.

This means that $n = 1664, \pi = \frac{939}{1664} = 0.5643$

95% confidence level

So $\alpha = 0.05$ , z is the value of Z that has a pvalue of $1 - \frac{0.05}{2} = 0.975$ , so $Z = 1.96$ .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.5643 - 1.96\sqrt{\frac{0.5643*0.4357}{1644}} = 0.54$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.5643 + 1.96\sqrt{\frac{0.5643*0.4357}{1644}} = 0.588$

The 95% confidence interval for the proportion of all adult Americans who would give themselves a grade of A or B on their financial knowledge of personal finance is (0.54, 0.588). This means that we are 95% sure that the true proportion of all adult Americans who would give themselves a grade of A or B on their financial knowledge of personal finance is between these two bounds.

(b) Is the confidence interval from part (a) consistent with the statement that a majority of adult Americans would give themselves a grade of A or B?

Yes, because the confidence interval is entirely above 0.5.

Because this confidence interval is entirely above 0.5, the interval is consistent with the statement that a majority of adult Americans would give themselves a grade of A or B.

8 0

2 years ago

(a) An article in a medical journal suggested that approximately 14% of such operations result in complications. Using this esti

aev [14]

This question is incomplete, the complete question is;

Surgical complications: A medical researcher wants to construct a

99.5% confidence interval for the proportion of knee replacement surgeries that result in complications.

- An article in a medical journal suggested that approximately 14% of such operations result in complications. Using this estimate, what sample size is needed so that the confidence interval will have a margin of error of 0.08?

Answer: a sample of operations needed is 149

Step-by-step explanation:

Given that;

confidence interval = 99.5% = 0.995 so

margin of error E = 0.08

p = 14% = 0.14

now we obtain the critical value of z t the 99.5 confidence interval

∝ = 1 - confidence interval

∝ = 1 - 0.995

∝ = 0.005

∝/2 = 0.0025

obtaining the area of probability in the right tail

Area of probability to the right is = 1 - 0.0025 = 0.9975

from probability table; critical value of t =2.81

using the formula

n = p( 1 - p ) [ (z_∝/2)/E)² ]

so we substitute

n = 0.14 ( 1 - 0.14 ) [ 2.81 / 0.08 )²

n = (0.14 × 0.86 ) × 1233.7656

n = 148.5453 ≈ 149

Therefore , a sample of operations needed is 149

4 0

3 years ago

When a number is a multiple of 6 what are possible values of the ones digit

umka21 [38]

6,2,8,4,and 0 are the only possible value of the ones digit, because
6*1=6, last digit is 6
6*2=12, last digit is 2
6*3=18, last digit is 8
6*4=24, last digit is 4
6*5=30, last digit is 0
6*6=36, last digit is 6
and the whole cycle goes over again.

8 0

3 years ago