17% Any object that is floating will display the volume of fluid that matches the mass of the object that's floating. So if the object is 100% as dense as the fluid, it will just barely sink, if it's 50% as dense as the fluid, 50% will be submerged, etc. So let's see what percent of mercury's density is concrete. 2.3x10^3 / 13.6x10^3 = 0.169117647 = 16.9117647% Rounding to 2 significant figures gives 17%. So 17% of a piece of concrete will be submerged in mercury when it's floating in mercury.

3 0

3 years ago

The sound intensity of a certain type of food processor in normally distributed with standard deviation of 2.9 decibels. If the

Maru [420]

Answer: $(48.41,\ 52.19)$

Explanation:

The confidence interval for population mean is given by :-

$\overline{x}\pm z_{\alpha/2}\dfrac{\sigma}{\sqrt{n}}$

Given : Sample size : $n=9$

Sample mean : $\ovreline{x}=50.3\text{ decibels}$

Standard deviation : $\sigma=2.9\text{ decibels }$

Significance level : $\alpha=1-0.95=0.05$

Critical value : $z_{\alpha/2}=z_{0.025}=1.96$

Now, the 95% confidence interval estimate of the (true, unknown) mean sound intensity of all food processors of this type :-

$50.3\pm (1.96)\dfrac{2.9}{\sqrt{9}}\\\\\approx50.3\pm1.89\\\\=(50.3-1.89,\ 50.3+1.89)=(48.41,\ 52.19)$

6 0

3 years ago

4. A family leaves from New York City and is flying to Los Angles which is 2800mi away. It takes

Blizzard [7]

The average speed of the whole travel is equal to 400 mph.

Why?

From the statement, we know that whole travel is divided into three parts. For the first part (traveling from New York to Chicago), we have that it was 3.25 hours and the covered distance was half of the total distance (1400mi). For the second part, we have that it was 1 hour (layover time), and the covered no distance. For the third part (traveling from Chicago to Los Angeles), we have that it was 2.75 hours, and it took the other half of the total distance (1400mi).

We can calculate the average speed of the whol travel using the following formula:

$AverageSpeed=\frac{distance_{1}+distance_{2}+distance_{3}}{time_{1}+time{2}+time_{3}}$

Now, substituting and calculating, we have:

$AverageSpeed=\frac{1400mi+0mi+1400mi}{3.25h+1h+2.75h}$

$AverageSpeed=\frac{2800mi}{7h}=400mph$

Hence, we have the average speed of the whole travel is equal to 400 mph.

Have a nice day!

7 0

4 years ago