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2 years ago

MATH AND PERCENTAGES

Mathematics

2 answers:

Ilia_Sergeevich [38]2 years ago

6 0

Answer:

3 dollars

Step-by-step explanation:

Anit [1.1K]2 years ago

5 0

The answer is 3 dollars

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Simplify the following expression.<br> <br> 15p+15p+25p =

IrinaK [193]

15p+15p+25p=30p+25p=55p

3 0

2 years ago

The ratio of girls to boys in the 6th grade is to 6to7 how many girls are there if there are 364total students

Rina8888 [55]

Answer:

168 girls.

Step-by-step explanation:

There are a total of 6 + 7 = 13 'parts'.

So one part = 364 / 13 = 28.

So the number of girls = 6 * 28

= 168.

4 0

2 years ago

A wheel with radius 1 foot makes 1 revolution in 4 seconds. What is the linear velocity, in feet per second, of a point on the e

3241004551 [841]

Radius = r = 1 foot

Angular velocity = w = 1 revolutions in 4 seconds

So,

w = 0.25 revolutions per second

Since,

1 revolution = 2π radians

We can write the above equation as:

w = 0.25 x 2π radians per second = 0.5π radians per second

Linear Velocity = v = r w

Using the values, we can write:

v = 1 x 0.5π

= 0.5 π

= π/2 feet per second

Therefore, the correct answer is option B

7 0

2 years ago

Read 2 more answers

Pleasantburg has a population growth model of P(t)=at2+bt+P0 where P0 is the initial population. Suppose that the future populat

yulyashka [42]

Answer:

The population will reach 34,200 in February of 2146.

Step-by-step explanation:

Population in t years after 2012 is given by:

$P(t) = 0.8t^{2} + 6t + 19000$

In what month and year will the population reach 34,200?

We have to find t for which P(t) = 34200. So

$P(t) = 0.8t^{2} + 6t + 19000$

$0.8t^{2} + 6t + 19000 = 34200$

$0.8t^{2} + 6t - 15200 = 0$

Solving a quadratic equation:

Given a second order polynomial expressed by the following equation:

$ax^{2} + bx + c, a\neq0$ .

This polynomial has roots $x_{1}, x_{2}$ such that $ax^{2} + bx + c = a(x - x_{1})*(x - x_{2})$ , given by the following formulas:

$x_{1} = \frac{-b + \sqrt{\bigtriangleup}}{2*a}$

$x_{2} = \frac{-b - \sqrt{\bigtriangleup}}{2*a}$

$\bigtriangleup = b^{2} - 4ac$

In this question:

$0.8t^{2} + 6t - 15200 = 0$

So $a = 0.8, b = 6, c = -15200$

Then

$\bigtriangleup = 6^{2} - 4*0.8*(-15100) = 48356$

$t_{1} = \frac{-6 + \sqrt{48356}}{2*0.8} = 134.14$

$t_{2} = \frac{-6 - \sqrt{48356}}{2*0.8} = -141.64$

We only take the positive value.

134 years after 2012.

.14 of an year is 0.14*365 = 51.1. The 51st day of a year happens in February.

So the population will reach 34,200 in February of 2146.

6 0

2 years ago

The dwarves of the Grey Mountains wish to conduct a survey of their pick-axes in order to construct a 99% confidence interval ab

Dmitry_Shevchenko [17]

Answer:

The minimum sample size needed is 125.

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 $1 - \frac{\alpha}{2}$ .

The margin of error is:

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

For this problem, we have that:

$\pi = 0.25$

99% confidence level

So $\alpha = 0.01$ , z is the value of Z that has a pvalue of $1 - \frac{0.01}{2} = 0.995$ , so $Z = 2.575$ .

What minimum sample size would be necessary in order ensure a margin of error of 10 percentage points (or less) if they use the prior estimate that 25 percent of the pick-axes are in need of repair?

This minimum sample size is n.

n is found when $M = 0.1$