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3 years ago

Help with #4 please.

Mathematics

2 answers:

Harlamova29_29 [7]3 years ago

8 0

The Answer would be B

mojhsa [17]3 years ago

5 0

The answer would be B

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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

2 years ago

Read 2 more answers

Herodoto, historiador

Masja [62]

Answer:

Defining the straight number of integers, we have to live in the year 2020 and this Greek historian was born in the year - 484.

Step-by-step explanation:

When using whole numbers, we denote positive numbers as the number of numbers after 0, and negative numbers the number of numbers before zero.

So if we consider the birth of Christ to be the year 0, then all years before Christ will be negative and all years after Christ will be positive.

So we have to live in the year 2020 and this Greek historian was born in the year - 484.

3 0

3 years ago

Find the total surface area of this cuboid. 6cm 5cm 4cm

shusha [124]

Answer:

148cm^2

Step-by-step explanation:

The formula for surface area of a rectangular prism is 2(hl)+2(hw)+2(wl).

we just plug in the values.

2(6 x 5) + 2(6 x 4) + 2(4 x 5)

= 2(30) + 2(24) + 2(20) then simplify

= 60 + 48 + 40

= 148

6 0

2 years ago

One population proportion test: Which of the following situations involves testing a claim about a single population proportion?

xenn [34]

Answer:

A recent report estimated that 25% of all college students in the United States have a sexually transmitted disease (STD). The director of the campus health center believes that the proportion of students with STDs is higher at their campus.

According to the American Heart Association guidelines, the daily maximum amount of sugar a teenager should have is 4 teaspoons. The parents of a local high school have expressed concerns that the average daily sugar intake of their students is higher than these guidelines and have been pressuring school officials to limit unhealthy snack and beverage choices offered in the cafeteria and student store.

Step-by-step explanation:

The first two researches involve the single sample compared to mean of population.

The 3rd and 4th research involves comparing samples of men and women that is two individual groups.

6 0

3 years ago

Oliga [24]

I’m not sure what the answer is, just trying to get points.... but I hope you find your answer :)

4 0

3 years ago