Select from the drop-down menus to correctly complete each statement.

A sample survey is designed to estimate the proportion of sports utility vehicles being driven in the state of California. A ran

mart [117]

Answer:

a) The 95% confidence interval would be given (0.070;0.121).

b) "increase the sample size n"

"decrease za/2 by decreasing the confidence"

Step-by-step explanation:

Notation and definitions

$X=48$ number of vehicles classified as sports utility.

$n=500$ random sample taken

$\hat p=\frac{48}{500}=0.096$ estimated proportion of vehicles classified as sports utility vehicles.

$p$ true population proportion of vehicles classified as sports utility vehicles.

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})$

(a) Use a 95% confidence interval to estimate the proportion of sports utility vehicles in California. (Round your answers to three decimal places.)

The confidence interval would be given by this formula :

$\hat p \pm z_{\alpha/2} \sqrt{\frac{\hat p(1-\hat p)}{n}}$

For the 95% confidence interval the value of $\alpha=1-0.5=0.05$ and $\alpha/2=0.025$ , with that value we can find the quantile required for the interval in the normal standard distribution.

$z_{\alpha/2}=1.96$

And replacing into the confidence interval formula we got:

$0.096 - 1.96 \sqrt{\frac{0.096(1-0.096)}{500}}=0.070$

$0.096 + 1.96 \sqrt{\frac{0.096(1-0.096)}{500}}=0.121$

And the 95% confidence interval would be given (0.070;0.121).

We are confident (95%) that about 7.0% to 12.1% of vehicles in California are classified as sports utility .

(b) How can you estimate the proportion of sports utility vehicles in California with a higher degree of accuracy? (HINT: There are two answers. Select all that apply.)

For this case we just have two ways to increase the accuracy one is "increase the sample size n" since if we have a larger sample size the estimation would be more accurate. And the other possibility is "decrease za/2 by decreasing the confidence" because if we decrease the confidence level the interval would be narrower and accurate

7 0

3 years ago

A person wishes to mix coffee worth nine dollars per pound with coffee worth three dollars per pound to get 240 pounds of a mixt

Anastasy [175]

$\bf \begin{array}{lccclll}
&amount&price&priced\ amount\\
&-----&-----&--------\\
\textit{9 bucks/lb}&x&9&9x\\
\textit{3 bucks/lb}&y&3&3y\\
-----&-----&-----&-------\\
mixture&240&5&1200
\end{array}
\\\\\\
\begin{cases}
x+y=240\implies \boxed{y}=240-x\\
9x+3y=1200\\
----------\\
9x+3\left( \boxed{240-x} \right)=1200
\end{cases}$

solve for "x".

what about "y"? well, y = 240 - x

4 0

4 years ago

Is the function increasing or decreasing over the interval [-3, -1)? Explain.

olga nikolaevna [1]

Answer:I actually don’t know

Step-by-step explanation:

4 0

3 years ago

Whoever answers question 19 correctly with both parts of the questions answered

diamong [38]

Let's focus on 0.7*0.8 for now.

Start by drawing a large square. Cut this figure into 10 rows and 10 columns. So this means you'll have 10*10 = 100 little squares.

Now highlight the first 7 rows. Shade in all 70 squares (7*10 = 70)
Starting on the left side, highlight the first 8 columns. You'll shade in 80 squares (8*10 = 80)

Use different colors for your highlighting or somehow indicate different shading styles. This way you can see the overlapping region. The overlapping region consists of 56 squares (7 rows, 8 columns ---> 7*8 = 56 little squares)

Each little square represents 0.01, so having 56 of them means we have 0.56

This shows that 0.7*0.8 = 0.56

-----------------------------------------------------------

How is this different if we had 1.7*0.8? Well we can break 1.7 into 1+0.7 to have

1.7*0.8 = (1+0.7)*0.8
1.7*0.8 = (1)*0.8+(0.7)*0.8
1.7*0.8 = (1*0.8)+(0.7*0.8)

The portion (0.7*0.8) was done earlier. That result was 0.56. So we just need to compute (1*0.8), which is simply 0.8; recall that 1 times any number is that number itself.

Now simply add 0.8 to 0.56 to get 1.36

So, 1.7*0.8 = 1.36

5 0

4 years ago

A customer desires to mix her own concrete. The clerk knows that the ratio of cement to sand to gravel is 1:3:4. If the customer

Aleks [24]

Answer:

The quantity of cement use is 125 pounds

The quantity of sand use is 375 pounds

The quantity of gravel use is 500 pounds

Step-by-step explanation:

Given as :

The ratio of cement to sand to gravel = 1 : 3 : 4

The total quantity of dry mix required = 1000 pounds

Let The quantity of cement required = 1 × x pounds

The quantity of sand required = 3 × x pounds

The quantity of gravel required = 4 × x pounds

So, According to question

The total quantity of dry mix required = The quantity of cement required + The quantity of sand required + The quantity of gravel required

Or, x + 3 x + 4 x = 1000 pounds

Or, 8 x = 1000 pounds

∴ x = $\frac{1000}{8}$

I.e x = 125

So , The quantity of cement required = 1 × 125 pounds = 125 pounds

The quantity of sand required = 3 × 125 pounds = 375 pounds

The quantity of gravel required = 4 × 125 pounds = 500 pounds

Hence The quantity of cement use is 125 pounds

The quantity of sand use is 375 pounds

The quantity of gravel use is 500 pounds

Answer

8 0

3 years ago