Not sure how to do this

Mathematics

1 answer:

OLEGan [10]3 years ago

8 0

It's pretty simple! So it looks like you are learning proportions. You would cross multiply to achieve your answer.

First, let's do your first problem:

2 12
--- = ----
5 n

You would take 5 and multiply it by 12 and get 60! Then you would do the same with 2 times n, giving you 2n (because you do not know what n represents YET.)

Now you should have this:
60=2n OR 2n=60

We must isolate our variable, in order to do that, get rid of two! But how? You would do this by dividing 2n by 2. Yet in equations, when you do something to one side, you must do it to the other because they must be EQUAL! (hence the "equa-" in equation)

2n=60
--- ---
2 2 DIVIDE 2 into 60
----------
n= 30 Simplify!

Your final answer for the first question is n= 30!

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Two children own two-way radios that have a maximum range of 3 miles. One leaves a certain point at 1:00 P.M., walking due north

Grace [21]

Answer:

The answer is 21 minutes

Step-by-step explanation:

We use the equation Xf = Xo + vt

1) At 1:00 PM, child one leaves the starting point heading north at a constant velocity of 6 mi/hr or .1 [mi/min] (divide by 60 to convert from [mi/hr] to [mi/min])

2) He walks for 15 minutes before kid 2 starts walking. In 15 minutes he is able to cover 1.5 [mi]

$x_{1f1} =x_{o} +v_{1} t_{1} \\x_{1f1} =0+.1(15)\\x_{1f1} =1.5 [mi]$

3) Now, child 2 starts walking and we know that when the range reaches 3 miles, they won´t be able to communicate. So the sum of the final position of child 1 and child 2 must be 3[mi]

Child 1 final position => $x_{1f} = x_{1f1} +v_{1} t\\x_{1f} =1.5+v_{1} t$
Child 2 final position => $x_{2f} =0+v_{2} t$

4) Sum the equations and equate to 3

$x_{1f} +x_{2f} =3$

5) Substitute the values we already know

$1.5+v_{1} t+v_{2}t=3\\ 1.5+.1t+.15t=3\\1.5+.25t=3\\t=\frac{3-1.5}{.25} \\t=6 [min]$

6) in 15 + 6 minutes they will be 3miles apart

7) In 21 minutes they will still be able to communicate with one another.

7 0

3 years ago

carley beat the school record for the 400 meter run by 1.3 seconds. if she ran the race in 55.7 seconds what was the record?

Vika [28.1K]

Answer:

If Carley ran the 400 meter run in a total of 55.7 seconds and she beat the record by 1.3 seconds, you would add 55.7 and 1.3

55.7+1.3= 57 seconds

The past school record for the girls 400 meter run was 57 seconds

Hope this helps ;)

4 0

3 years ago

The graph below represents which system of inequalities? graph of two infinite lines that intersect at a point. One line is soli

stiks02 [169]

The first line through points (-3, 0) and (-4, -1) is the orange line.

The second line, through (1, 1) and (2, -1) is the purple line.

Since they are both shaded below, the intersection of the shaded regions, is the region colored in blue.

Both lines are included, since they are solid lines.

The equation of the first line can be found as follows:

the slope is $\frac{0-(-1)}{-3-(-4)}=\frac{1}{1}=1$ , thus, the equation is:
$y-0=1(x-(-4))\\\\y=x+4$

The equation of the second line can be found as follows:

the slope is $\frac{1-(-1)}{1-2}= \frac{2}{-1}=-2$ ,

thus the equation of the second line is :

$y-1=-2(x-1)\\\\y-1=-2x+2\\\\y=-2x+3$

We have to decide on the direction of the inequality sign, so we pick a point, for example (0, 4) which is not in the colored regions of the lines,

so we write the inequalities so that they do not hold for (0, 4)

line 1:

y≥x+4

4≥0+4=4 is true, so we change the sign and write : y≤x+4

similarly, line 2:

y≤-2x+3

4≤-2*0+3=3, which is not true, so we have the correct direction.

Note that since the lines were solid, we include the equality case:

Answer:

the shaded region is the solution to the system of inequalities:

i) y≤x+4
ii) y≤-2x+3