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erma4kov [3.2K]
3 years ago
6

One person can do a certain job in twenty-one minutes, and another person can do the same job in twenty-eight minutes. How many

minutes will it take them to do the job together?
6 min
12 min
24 min
Mathematics
2 answers:
grigory [225]3 years ago
6 0

the correct answer is 12

MrMuchimi3 years ago
6 0

Answer: 12 min

Step-by-step explanation:

Given: Time taken by one person to do a job = 21 minutes

Time taken by another person to do a the same job = 28 minutes

If they work together then the total time taken by both of them to complete the job is given by :-

\frac{1}{T}=\frac{1}{21}+\frac{1}{28}\\\\\Rightarrow\frac{1}{T}=\frac{4+3}{84}\\\\\Rightarrow\frac{1}{T}=\frac{7}{84}\\\\\Rightarrow\frac{1}{T}=\frac{1}{12}\\\\\Rightarrow T=12

Hence, they will take 12 minutes to do the job together.

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Lunna [17]
1. 4 3/4 feet = 19/4 feet
2 2/5 feet=12/5 feet.
multiplying them together yields 
\frac{19}{4} * \frac{12}{5} =
=  \frac{57}{5} = 11.4 ft^{2}

Part 2: 
11.4 ft^2 - 4 1/2 ft^2=
11.4-4.5=6.9 ft^2 = 69/10 ft^2 left after you subtract the decoration in the middle
Now you're trying to find now many rectangular cutouts (that each are 3/8 ft^2) will fit in the remaining space.
You do that by dividing the remaining space left by 3/8:
\frac{69}{10} / \frac{3}{8} =  \frac{69}{10} * \frac{8}{3} =  \frac{92}{5}
since you have to have a whole number of cutouts, you round 92/5 down to 90/5, which is 18 cutouts
5 0
3 years ago
A kite ascends at a rate of 30 feet per minute. What is the elevation after 6.5 minutes
Sever21 [200]

Answer:

195 feet.

Step-by-step explanation:

multiply 30 x 6.5.

8 0
3 years ago
20. In the image, ABC has measure 58°. What is the measure of ABD?
PolarNik [594]

Answer:

Option B, 29°

Step-by-step explanation:

The diagram is a angle bisecting diagram which divides the 58° angle into two 29° angles.

Answered by GAUTHMATH

3 0
2 years ago
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geniusboy [140]

Answer:

A.) the function is increasing on the interval (-∞, 0) and decreasing on interval (0,∞)

Step-by-step explanation:

7 0
2 years ago
Triangle RST has the vertices R(2, 3), S(-2, 1), and T(-1, 5). What are the coordinates after the two transformations: Translati
igor_vitrenko [27]

Given :

Triangle RST has the vertices R(2, 3), S(-2, 1), and T(-1, 5).

To Find :

The coordinates after the two transformations:

a) Translation (x, y) --> (x - 2, y - 1) .

b)  Rotation: 90 degrees counterclockwise at the origin.

Solution :

Applying transition a) , we get :

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R'( 0, 2) , S'( -4 , 0), T'( -3, 4)

Now , When any point ( h , k ) is rotated 90° counterclockwise about the origin, the new points are (-k , h) .

So , R''( -2, 0) , S''( 0, -4 ) , T''( -4 , -3 ) .

Therefore , the coordinates after transformations are

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Hence , this is the required solution .

6 0
3 years ago
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