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Lilit [14]
3 years ago
10

Two grandparents want to pick up the mess that their granddaughter had made in her playroom. One can do it in 15 minutes working

alone. The​ other, working​ alone, can clean it in 12 minutes. How long will it take them if they work​ together?
Mathematics
1 answer:
Crank3 years ago
5 0

Answer:

  6 2/3 minutes

Step-by-step explanation:

Their rates in "jobs per hour" are ...

  (60 min/h)/(15 min/job) = 4 jobs/h

and

  (60 min/h)/(12 min/job) = 5 jobs/h

So, their combined rate is ...

  (4 jobs/h) + (5 jobs/h) = 9 jobs/h

The time required (in minutes) is ...

  (60 min/h)/(9 jobs/h) = (60/9) min = 6 2/3 min

Working together, it will take them 6 2/3 minutes.

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kogti [31]
3(4x +12)=180
12x + 36 =180
-36. -36
180-36= 144
12x = 144
——. ——-
12. 12
X = 12
6 0
3 years ago
I conclude from the information given that he is just very lucky. I believe he is lucky, because it is very hard to perform tric
VikaD [51]

Answer:

I believe that the owner of the dice is actually not lucky. There are people who practice throwing dice in a controlled way in order to get a specific side of the dice. If he practices his dice throwing a lot, then he would have a much higher chance of winning at a game of dice.

Step-by-step explanation:

Since you said he was lucky, I decided to make an answer saying that he wasn't lucky so you can choose between both of them. Your answer was good as well.

7 0
2 years ago
Describe what happens when two intersecting lines form a linear pair of congruent angles. Explain how you can get eight congruen
Charra [1.4K]
The angles diagonally opposite each other are congruent while those adjacent to each other add up to 180 degrees. You can get eight congruent angles with a transversal if the two lines are parallel, because each angle would be 90.
6 0
3 years ago
a rectangular block is such that the sides of its base are of the length x cm and 3x cm. The sum of all the lengths of all its e
Xelga [282]

Answer:

15x^2 - 12x^3

Step-by-step explanation:

A rectangular block has 3 parts that play into its volume.  length, width and height.  The question gives us length and width in the form of x and 3x, so height is what's missing.

It gives us a bit more information saying the sum of its edges is 20.  We also have to ask how many lengths, widths and heights are there.  That may be a bit hard to understand, but  is you are looking at a block I could ask how many edges are vertical, just going up and down.  These would be the heights.  There are 4 total, and this goes the same for length and width, so 4*length + 4*width and 4*height = 20.  

Taking that and plugging in x for length and 3x for width (or you could do it the other way around, it doesn't matter, you get:

4*x + 4*3x + 4*height = 20

4x + 12x + 4h = 20

16x + 4h = 20

4h = 20 - 16x

h = 5 - 4x

Now we have h in terms of x, which lets us easily find the volume just knowing x.  To find the volume of a rectangular block you just multiply the length, width and height.

x*3x*(5-4x)

3x^2(5-4x)

15x^2 - 12x^3

Question doesn't give a specific value for x at all so you should be done there.  Any number you plug in for x should get you the right answer

5 0
2 years ago
A soft drink manufacturer wishes to know how many soft drinks adults drink each week. They want to construct a 85% confidence in
andreev551 [17]

Answer: 547

Step-by-step explanation: The margin of error formulae is given below as

Margin of error = critical value ×(σ/√n)

Where σ = standard deviation and n is the sample size.

From our question, margin of error = 0.08

Variance is 1.691,

hence σ = √variance = √1.691

= 1.3.

We will be using a z test for our critical value this is because a soft drink manufacturer will always produce drinks more than 30 in numbers.

The critical value for a 85% confidence interval is 1.44.

Hence critical value is 1.44.

By substituting the parameters, we have that

0.08 = 1.44 × 1.3/ √n

0.08 = 1.873/ √n

By cross multiplying

0.08 × √n = 1.873

√n = 1.873/ 0.08

√n = 23.41

n = (23.41)²

n = 547.

7 0
3 years ago
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