Choose all the factor pairs of 12. A. 1,12 B. 2,6 C. 3,4 D. 5,7 E. 6,6

Dwayne drove 18 miles to the airport to pick up his father and then returned home. On the return trip he was able to drive an av

Nesterboy [21]

Answer:

30 mph

Step-by-step explanation:

Let d = distance (in miles)

Let t = time (in hours)

Let v = average speed driving to the airport (in mph)

⇒ v + 15 = average speed driving from the airport (in mph)

Using: distance = speed x time

$\implies t=\dfrac{d}{v}$

Create two equations for the journey to and from the airport, given that the distance one way is 18 miles:

$\implies t=\dfrac{18}{v} \ \ \textsf{and} \ \ t=\dfrac{18}{v+15}$

We are told that the total driving time is 1 hour, so the sum of these expressions equals 1 hour:

$\implies \dfrac{18}{v} +\dfrac{18}{v+15}=1$

Now all we have to do is solve the equation for v:

$\implies \dfrac{18(v+15)}{v(v+15)} +\dfrac{18v}{v(v+15)}=1$

$\implies \dfrac{18(v+15)+18v}{v(v+15)}=1$

$\implies 18(v+15)+18v=v(v+15)$

$\implies 18v+270+18v=v^2+15v$

$\implies v^2-21v-270=0$

$\implies (v-30)(v+9)=0$

$\implies v=30, v=-9$

As v is positive, v = 30 only

So the average speed driving to the airport was 30 mph

(and the average speed driving from the airport was 45 mph)

8 0

1 year ago

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PLEASE help me! I need this by Today!! anyone

geniusboy [140]

Answer:

x=12

Step-by-step explanation:

Cross multiply them:

84 = 7x

Divide By 7 on both sides

12 = x

And there is the answer. Sorry I couldn't explain better Im really not feeling good today

3 0

1 year ago

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A car requires 22 liters of petrol to travel a distance of 259.6 km. Find the amount that the car owner has to pay to travel a d

podryga [215]

Answer:

Step-by-step explanation:

22 liters of petrol to travel 259.6 km

1litres will travel 259.6/22 km

1litres will travel 11.8km

:2013.2km needs 2013.2/11.8litre

:2013.2km needs 170.61litres

And 1 liter of petrol costs $ 1.99

So 742.88 litres will cost $1.99×170.61

= $339.51

6 0

3 years ago

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PLEASE I NEED HELP NOW!!!!

const2013 [10]

Answer:

80

Step-by-step explanation:

filler text filler text filler text

5 0

3 years ago

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The department of public safety has an old memo stating that the number of accidents per week at a hazardous intersection varies

ELEN [110]

Answer:

P-value = 0.1515

Step-by-step explanation:

We are given the following in the question:

Population mean, μ = 2.2

Sample mean, $\bar{x}$ = 2

Sample size, n = 52

Alpha, α = 0.05

Population standard deviation, σ = 1.4

First, we design the null and the alternate hypothesis

$H_{0}: \mu =2.2\\H_A: \mu < 2.2$

We use one-tailed(left) z test to perform this hypothesis.

Formula:

$z_{stat} = \displaystyle\frac{\bar{x} - \mu}{\frac{\sigma}{\sqrt{n}} }$

Putting all the values, we have

$z_{stat} = \displaystyle\frac{2 - 2.2}{\frac{1.4}{\sqrt{52}} } = -1.03$

Now, we calculate the p-value from the normal standard table.

P-value = 0.1515

6 0

2 years ago