85 is 50% of what number

QUESTION 2

Mekhanik [1.2K]

Answer:

3/30 =1/10

Step-by-step explanation:

add up the number of balls and then

number of black balls divided by the total number of balls.

5 0

3 years ago

Calculate a and b if

const2013 [10]

Notice that

$7^{2014} - 7^{2012} = 7^{2012} \bigg(7^2 - 1\bigg) = 7^{2012} \times 48 = 2^4 \times 3 \times 7^{2012}$

$12=2^2\times3$ , so

$\dfrac{7^{2014}-7^{2012}}{12} = 2^2 \times 7^{2012}$

Then taking the positive square root gives

$\sqrt{\dfrac{7^{2014}-7^{2012}}{12}} = \sqrt{2^2 \times 7^{2012}} = 2\times7^{1006}$

so $\boxed{a=2}$ and $\boxed{b=1006}$ .

4 0

1 year ago

The Paralyzed Veterans of America is a philanthropic organization that relies on contributions. They send free mailing labels an

lions [1.4K]

Answer:

Confidence interval: (0.04649,0.04913)

Step-by-step explanation:

We are given the following in the question:

Sample size, n = 100,000

Number of people who donated, x = 4781

$\hat{p} = \dfrac{x}{n} = \dfrac{4781}{100000} = 0.04781
$

95% Confidence interval:

$\hat{p}\pm z_{stat}\sqrt{\dfrac{\hat{p}(1-\hat{p})}{n}}$

$z_{critical}\text{ at}~\alpha_{0.05} = 1.96$

Putting the values, we get:

$0.04781
\pm 1.96(\sqrt{\dfrac{0.04781
(1-0.04781
)}{100000}})\\\\=0.04781
\pm 0.00132\\\\=(0.04649,0.04913)$

is the required 95% confidence interval for the true proportion of their entire mailing list who may donate.

3 0

2 years ago

Write out the first few terms of the series Summation from n equals 0 to infinity (StartFraction 2 Over 3 Superscript n EndFract

anyanavicka [17]

Answer:

$\sum\limits_{n=0}^{\infty} \frac{2}{3^n}\frac{(-1)^n}{5^n} = 15/8$

Step-by-step explanation:

The sum you are trying to understand is this.

$\sum\limits_{n=0}^{\infty} \frac{2}{3^n}\frac{(-1)^n}{5^n}$

Remember that in general when you have a geometric series

$\sum\limits_{n = 0}^{\infty} a*r^n$ you have that

$\sum\limits_{n = 0}^{\infty} a*r^n = \frac{a}{1-r}$ and that equality is true as long as $|r| < 1$ .

Therefore here we have

$\sum\limits_{n=0}^{\infty} \frac{2}{3^n}\frac{(-1)^n}{5^n} = \sum\limits_{n=0}^{\infty} 2* \big(\frac{-1}{3*5} \big)^n = \sum\limits_{n=0}^{\infty} 2* \big(\frac{-1}{15} \big)^n$ and $\big|\frac{-1}{15} \big| = \frac{1}{15} < 1$

Therefore we can use the formula and

$\sum\limits_{n=0}^{\infty} 2* \big(\frac{-1}{15} \big)^n = \frac{2}{1-(-1/15)} = \frac{2}{1+1/15} = 30/16 = 15/8$

5 0

2 years ago

A new novel is selling for $17.95. If it is on sale at 40% off, find the amount of discount and the sale price.

nadya68 [22]

Answer:

A

Step-by-step explanation:

multiply $17.95 by 40% to get the discount ($17.95 x .4), which equals $7.18.

the sale price is the initial price of the book less the discount ($17.95-$7.18), which equals $10.77.

5 0

2 years ago