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Schach [20]
3 years ago
8

A rubber ball is dropped from the top of a hole. Exactly 20 seconds later, the sound of the rubber ball hitting bottom is heard.

How deep is the hole? (Hint The distance that a dropped object falls in t seconds is represented by the formula s= 167. The speed of sound is 1100 ft/sec.)​
Mathematics
1 answer:
gayaneshka [121]3 years ago
7 0

9514 1404 393

Answer:

  4192.9 ft

Step-by-step explanation:

We assume your falling-distance formula is supposed to be ...

  s = 16t²

So, the time required to fall distance s is ...

  t = √(s/16) = (1/4)√s

The time required for sound to travel distance s is ...

  s = 1100t

  t = s/1100

Then the sum of the time for the ball to fall and the time for the sound to travel back is ...

  (1/4)√s + s/1100 = 20

  275√s = 22000 -s . . . . . multiply by 1100 and subtract s

  75625s = s^2 -44000s +484,000,000 . . . square both sides

  s^2 -119,625s +484,000,000 = 0 . . . . put in standard form

  s ≈ (1/2)(119,625 ±√12,374,140,625) = {4192.943, 115432.057}

Only the smaller of these two solutions makes any sense in this problem.

The hole is about 4192.9 feet deep.

_____

<em>Additional comment</em>

The distance equation for the falling object presumes a vacuum. The sound transmission presumes the presence of air, so the question setup is self-contradictory.

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3 0
3 years ago
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Orbital Toys sells two types of sets of magnetic spheres, silver and brass. The store owner, Lucy Ball, pays $8 and $16 for each
sdas [7]

Answer:

The maximum profit will be reached by buying 500 brass magnetic spheres and 1500 silver magnetic spheres.

Step-by-step explanation:

In order to solve this you need to create a system of equations, with two values that will create the answer we are looking for, the thing that we don't know here is how many of each are we buying so the number of silver magnetic spheres will be represented by "y" and the brass magnetic spheres will be represented by "x".

So we know that x+y=2000

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We now just solve for one of them

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5 0
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Lerok [7]
Slope = (y2 - y1) / (x2 - x1)
(5,3)...x1 = 5 and y1 = 3
(8,-2)..x2 = 8 and y2 = -2
now we sub
slope = (-2 - 3) / (8 - 5) = -5 / 3

y = mx + b
slope(m) = -5/3
use either of ur points..(5,3)...x = 5 and y = 3
now we sub and find b, the y int
3 = -5/3(5) + b
3 = -25/3 + b
3 + 25/3 = b
9/3 + 25/3 = b
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ur equation is y = -5/3x + 34/3...but we need it in standard form

y = -5/3x + 34/3
5/3x + y = 34/3
5x + 3y = 34 <=== standard form
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