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Alchen [17]
3 years ago
14

Wilma can mow a lawn in 60 minutes. Rocky can mow the same lawn in 40 minutes. How long does it take for both Wilma and Rocky to

mow the lawn if they are working together?
Mathematics
1 answer:
UNO [17]3 years ago
3 0
<h3>Answer:  24 minutes</h3>

===================================================

Explanation:

Let's say the lawn is 120 square feet. I picked 120 as it is the LCM (lowest common multiple) of 60 and 40.

Since Wilma can mow the lawn in 60 minutes, her rate is 120/60 = 2 sq ft per minute. In other words, each minute means she gets 2 more square feet mowed. Rocky can do the full job on his own in 40 minutes, so his rate is 120/40 = 3 sq ft per minute.

Their combined rate, if they worked together (without slowing each other down), would be the sum of the two rates. So we get 2+3 = 5 sq ft per minute as the combined rate. The total time it would take for this 120 sq ft lawn is 120/5 = 24 minutes.

--------------------------

Another approach

Wilma takes 60 minutes to do the full job, so her rate is 1/60 of a lawn per minute. Rocky's rate is 1/40 of a lawn per minute. Their combined rate is

1/60 + 1/40 = 2/120 + 3/120 = 5/120 = 1/24 of a lawn per minute

x = number of minutes

(combined rate)*(time) = number of jobs done

(1/24)*x = 1

x = 1*24

x = 24 is the time it takes if they worked together without getting in each other's way.

Effectively, we are solving the equation

1/A + 1/B = 1/C

with

A = time it takes Wilma to do the job on her own

B = time it takes Rocky to do the job on his own

C = time it takes the two working together to get the job done

The equation above is equivalent to C*(1/A + 1/B) = 1 or (1/A + 1/B)*C = 1.

So basically you find the value of 1/A + 1/B, then find the reciprocal of this to get the value of C.

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Write two different expressions that<br> represent the quantity x decreased<br> by 30%.
s344n2d4d5 [400]

Answer:

Step-by-step explanation:

x - 30 = 14 - 3x

    4x = 44

      x = 11

Let's call the unknown number x

Now let's decrease it by 30, that is x-30

Now let's write out "14 decreased by three times the number", that is 14 - 3x

The problem says these are the same, that is x - 30 = 14 - 3x

We now want to isolate, or solve for, x

Move the x to one side of the equation by adding 3x to both sides

3x + x -30 = 14 - 3x + 3x

4x -30 = 14

Now move the 30 to the right hand side by adding 30 to both sides

4x - 30 + 30 = 14 + 30

4x = 44

Now all we have to do to get x is divide both sides by 4

4x/4 = 44/4

x = 11

4 0
2 years ago
The sum of the ages of Kristen and Ben is 32. Four years ago Kristen was twice as old as Ben. How old are they both now?
Elan Coil [88]

Let us say that:

K = age of Kristen

B = age of Ben

 

From the problem, we make the equations:

eqtn 1: K + B = 32

eqtn 2: (K – 4) = 2 (B – 4)

 

Simplifying eqtn 2:

K – 4 = 2 B – 8

K = 2 B – 4

 

Plugging in this to eqtn 2:

(2 B – 4) + B = 32

3 B – 4 = 32

3 B = 36

B = 12

 

From eqtn 2:

K = 2 B – 4 = 2 (12) – 4 = 20

 

So Kristen is 20 while Ben is 12.

5 0
3 years ago
How do i turn 24% into a fraction
PolarNik [594]
You can remove the % sign if you divide the number by 100:

\frac{24}{100}


This is because % is defined as 1/100, and the name (per-cent) actually meant this originally!
we can also simplify it: let's divide it by 4:

\frac{6}{25}




7 0
3 years ago
A Ferris wheel at the local fair has a diameter of 36 feet and a midline of 15 feet. This Ferris wheel makes one revolution ever
AVprozaik [17]

Answer:

Hold on let me seee!!!!!!!

5 0
3 years ago
Work out the volume of a cuboid <br> 10cm by 3cm by 2cm?
Firlakuza [10]
10 x 3 x 2 = the volume
10 x 3 = 30
30 x 2 = 60 cm^3
it is cm^3 because all of the numbers you have are in cm
8 0
3 years ago
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