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3 years ago

A copy machine makes 231 copies in 5 minutes and 15 seconds. How many copies does it make per minute?

Mathematics

1 answer:

kotykmax [81]3 years ago

7 0

Put 5 min 15 sec into seconds (315 seconds) and set up a ratio to find how many copies are made every 60 seconds.

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For the following telescoping series, find a formula for the nth term of the sequence of partial sums

gtnhenbr [62]

I'm guessing the sum is supposed to be

$\displaystyle\sum_{k=1}^\infty\frac{10}{(5k-1)(5k+4)}$

Split the summand into partial fractions:

$\dfrac1{(5k-1)(5k+4)}=\dfrac a{5k-1}+\dfrac b{5k+4}$

$1=a(5k+4)+b(5k-1)$

If $k=-\frac45$ , then

$1=b(-4-1)\implies b=-\frac15$

If $k=\frac15$ , then

$1=a(1+4)\implies a=\frac15$

This means

$\dfrac{10}{(5k-1)(5k+4)}=\dfrac2{5k-1}-\dfrac2{5k+4}$

Consider the $n$ th partial sum of the series:

$S_n=2\left(\dfrac14-\dfrac19\right)+2\left(\dfrac19-\dfrac1{14}\right)+2\left(\dfrac1{14}-\dfrac1{19}\right)+\cdots+2\left(\dfrac1{5n-1}-\dfrac1{5n+4}\right)$

The sum telescopes so that

$S_n=\dfrac2{14}-\dfrac2{5n+4}$

and as $n\to\infty$ , the second term vanishes and leaves us with

$\displaystyle\sum_{k=1}^\infty\frac{10}{(5k-1)(5k+4)}=\lim_{n\to\infty}S_n=\frac17$

7 0

3 years ago

Find the interest on a Principal Balance of $10,000 over the course of eight years with an interest rate of 5.5%. Do this for: S

o-na [289]

10,000$(1+0.055*8)
This is the formula of simple interest

10,000+10,000(0.055*t)
10,000$(1+0.055*8)=14,400

8 0

3 years ago

Read 2 more answers

Kenny's weight is 6/7 times melvin's weight. what is the ratio of melvin's weight to the total weight of the two boys?

dangina [55]

Answer=7:13

Kenny's Weight*6/7=Melvin's Weight

So, for example, if Melvin's weigh was 7...

Kenny's Weight*6/7=7
divide both sides by 6/7
Kenny Weight=6

So we can say that Melvin's weight to Kenny's weight is 7:6

The boys total weights would be...
7+6=13

So Melvin's weight over the total weight of the two boys is:

7:13

4 0

3 years ago

Read 2 more answers

It’s late work and I’ve forgotten how to do it

Veseljchak [2.6K]

You want to eliminate one of the terms (x or y) in one of the equations so you can solve for the other variable. You have to multiply by the opposite number of the coefficient to be able to eliminate the term in the other equation. If the x coefficient is 2, then you have to multiply the entire other equation by -2. If the y coefficient is -5, then you have to multiply the entire other equation by 5.

10)
-4x + 9y= 9
x - 3y= -6

STEP 1:
multiply the bottom equation by 4
4(x- 3y)= 4(-6)
4x - 12y= -24

STEP 2:
add the top equation and the equation from step 2

-4x + 9y= 9
4x - 12y= -24
the x term cancels out

-3y= 15
divide both sides by -3

y= -5

STEP 2:
substitute the y value in either original equation to solve for x

x - 3y= -6
x - 3(-5)= -6

x + 15= -6
subtract 15 from both sides

x= -21

ANSWER: x= -21; y= -5
____________________

12)
-7x + y= -19
-2x + 3y= -19

STEP 1:
multiply the top equation by -3 to eliminate the y term and to solve for x

-3(-7x + y)= -3(-19)
21x - 3y= 57

STEP 2:
add the bottom equation and the equation from step 2 to solve for x

-2x + 3y= -19
21x - 3y= 57
the y term cancels out

19x= 38
divide both sides by 19

x= 2

STEP 3:
substitute the x value in step 2 to solve for y; you can use either original equation

-7x + y= -19
-7(2) + y= -19

-14 + y= -19
add 14 to both sides

y= -5

ANSWER: x= 2; y=-5

Hope this helps! :)

4 0

3 years ago

Write the equation of a line that is perpendicular to the given line and that passes through the given point. y+2=1/3(x-5);(-4,3

wel

Here, equation of a line, y + 2 = 1/3 (x -5)
slope = 1/3

Slope of the line which is perpendicular would be -3 [ reciprocal & opposite ]

Now, y - y1 = m(x-x1)
y - 3 = -3(x - (-4))
y - 3 = -3x - 12
y = -3x - 9

In short, Your Answer would be y = -3x - 9

Hope this helps!

7 0

3 years ago