Ask question

Ask question

All categories

2 years ago

5

Justin is on a road trip. Over the past two days, he’s driven a total distance of 504 miles at an average speed of 56 miles/hour

. If Justin drove two hours today, he drove miles yesterday.

1 answer:

irakobra [83]2 years ago

8 0

Recall d = rt, distance = rate * time.

now, he has a speed rate of 56 mph for a distance of 504

$\bf d=rt\implies 504=56t\implies \cfrac{504}{56}=t\implies \stackrel{hours}{9}=t$

so, at that speed the whole driving time is 9 hours then. Ok, he drove 2 hours today, that means he drove 7 yesterday, 9 - 2.

how many miles is it for 7 hours at 56mph? d = rt ---> d = 56 * 7

that many miles he drove yesterday.

You might be interested in

Solve a = a+b+c+d/4 for c

kupik [55]

A=a+b+c+d/4
subtract a from both sides
0=b+c+d/4
Subtract b from both sides
-b=c+d/4
Finally subtract d/4 from both sides
c=-d/4-b

4 0

2 years ago

A candidate for a US Representative seat from Indiana hires a polling firm to gauge her percentage of support among voters in he

UkoKoshka [18]

Answer:

a) The minimum sample size is 601.

b) The minimum sample size is 2401.

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:

We dont know the true proportion, so we use $\pi = 0.5$ , which is when we are are going to need the largest sample size.

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 $Z = 1.96$ .

a. If a 95% confidence interval with a margin of error of no more than 0.04 is desired, give a close estimate of the minimum sample size that will guarantee that the desired margin of error is achieved. (Remember to round up any result, if necessary.)

This is n for which M = 0.04. So

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

$0.04 = 1.96\sqrt{\frac{0.5*0.5}{n}}$

$0.04\sqrt{n} = 1.96*0.5$

$\sqrt{n} = \frac{1.96*0.5}{0.04}$

$(\sqrt{n})^2 = (\frac{1.96*0.5}{0.04})^2$

$n = 600.25$

Rounding up

The minimum sample size is 601.

b. If a 95% confidence interval with a margin of error of no more than 0.02 is desired, give a close estimate of the minimum sample size necessary to achieve the desired margin of error.

Now we want n for which M = 0.02. So

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

$0.02 = 1.96\sqrt{\frac{0.5*0.5}{n}}$

$0.02\sqrt{n} = 1.96*0.5$

$\sqrt{n} = \frac{1.96*0.5}{0.02}$

$(\sqrt{n})^2 = (\frac{1.96*0.5}{0.02})^2$

$n = 2401$

The minimum sample size is 2401.

4 0

2 years ago

Write the following fractions in order from smallest to largest 3/10, 13/20, 22/25, 3/5

iren2701 [21]

Your answer from smallest to largest is:

3/10
3/5
13/20
22/25

6 0

3 years ago

B. If 3x - 3 and 5x + 7° are the angle of a linear pair, find their measurement the angle<br>

ankoles [38]

Answer:

x = 22°

the angles are: 63° and 117°

Step-by-step explanation:

a linear pair of angles total together to be 180°

so:

3x - 3 + 5x + 7 = 180

combune like terms:

8x = 176

divide both sides of the equation by 8:

x = 22°

the angles are: 63° and 117°

7 0

2 years ago

I need the answer for 21

levacccp [35]

Answer:

h>13

Step-by-step explanation:

3 0

2 years ago