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e-lub [12.9K]
3 years ago
10

A boat traveled 252 miles downstream and back. The trip downstream took 12 hours. The trip back took 84 hours. Find the speed of

the boat in still water and the speed of the current.
Mathematics
1 answer:
Leokris [45]3 years ago
7 0

Answer: the speed of the boat in still water is 12 mph and the speed of the current is 9 mph.

Step-by-step explanation:

Let x represent the speed of the boat in still water.

Let y represent the speed of the current.

The boat travelled 252 miles downstream and the same distance upstream.

The trip downstream took 12 hours. Assuming the boat travelled with the wind when going downstream, the total speed would be (x + y) mph.

Distance = speed × time

The expression for distance travelled downstream is

252 = 12(x + y)

Dividing through by 12, it becomes

21 = x + y- - - - - - - - - - 1

The trip back took 84 hours. Assuming the boat travelled against the wind when going back(upstream), the total speed would be (x - y) mph.

The expression for distance travelled upstream is

252 = 84(x - y)

Dividing through by 84, it becomes

3 = x - y- - - - - - - - - - 2

Adding equation 1 to equation 2, it becomes

24 = 2x

x = 24/2

x = 12 mph

Substituting x = 12 into equation 1, it becomes

21 = 12 + y

y = 21 - 12

y = 9 mph

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5. Priya mixes 2..5 cups of water with 1/3 cup or orange juice concentrate. Diego mixes 1 2/3 cups of water with 1/4 cup or oran
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Priya needs 13⅓ cups of orange juice

Diego 15 cups

Step-by-step explanation:

......................................................................................................................

Priya

......................................................................................................................

Cup of water = 2½

Cup of orange = ⅓

If 2½ cups of water requires ½ cup of orange juice concentrate

Then 100 cups of water would require x cup of orange

Representing the above statement mathematically

2½ : ⅓ = 100 : x

5/2 : 1/3 = 100 : x ------------------Convert ratio sign to division

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15/2 * x = 100/x * x

15x/2 = 100 ------------------ Multiply both sides by 2

2 * 15x/2 = 2 * 100

15x = 200 --------------- Divide both sides by 15

x = 200/15

x = 13⅓

So, 13⅓ cups of orange is needed by Priya

......................................................................................................................

Diego

......................................................................................................................

Cup of water = 1⅔

Cup of orange = ¼

If 1⅔ cups of water requires ¼ cup of orange juice concentrate

Then 100 cups of water would require x cup of orange

Representing the above statement mathematically

1⅔:¼ = 100:x

5/3 : ¼ = 100:x

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20/3 * x = 100/x * x

20x/3 = 100 ------------------------ Multiply 3 to sides by 3

3 * 20x/3 = 100 * 3

20x = 300 ------------- Divide both sides by 2

20x/20 = 300/20

x = 15

So, 15 cups of orange is needed by Diego

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Answer:

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