Round 547 to the nearest ten and hundred

bazaltina [42]

Answer:

I believe the answer is B

5 0

3 years ago

You are a lifeguard and spot a drowning child 60 meters along the shore and 40 meters from the shore to the child. You run along

sukhopar [10]

Answer:

The lifeguard should run across the shore a distance of 48.074 m before jumpng into the water in order to minimize the time to reach the child.

Step-by-step explanation:

This is a problem of optimization.

We have to minimize the time it takes for the lifeguard to reach the child.

The time can be calculated by dividing the distance by the speed for each section.

The distance in the shore and in the water depends on when the lifeguard gets in the water. We use the variable x to model this, as seen in the picture attached.

Then, the distance in the shore is d_b=x and the distance swimming can be calculated using the Pithagorean theorem:

$d_s^2=(60-x)^2+40^2=60^2-120x+x^2+40^2=x^2-120x+5200\\\\d_s=\sqrt{x^2-120x+5200}$

Then, the time (speed divided by distance) is:

$t=d_b/v_b+d_s/v_s\\\\t=x/4+\sqrt{x^2-120x+5200}/1.1$

To optimize this function we have to derive and equal to zero:

$\dfrac{dt}{dx}=\dfrac{1}{4}+\dfrac{1}{1.1}(\dfrac{1}{2})\dfrac{2x-120}{\sqrt{x^2-120x+5200}} \\\\\\\dfrac{dt}{dx}=\dfrac{1}{4} +\dfrac{1}{1.1} \dfrac{x-60}{\sqrt{x^2-120x+5200}} =0\\\\\\ \dfrac{x-60}{\sqrt{x^2-120x+5200}} =\dfrac{1.1}{4}=\dfrac{2}{7}\\\\\\ x-60=\dfrac{2}{7}\sqrt{x^2-120x+5200}\\\\\\(x-60)^2=\dfrac{2^2}{7^2}(x^2-120x+5200)\\\\\\(x-60)^2=\dfrac{4}{49}[(x-60)^2+40^2]\\\\\\(1-4/49)(x-60)^2=4*40^2/49=6400/49\\\\(45/49)(x-60)^2=6400/49\\\\45(x-60)^2=6400\\\\$

$x$

As $d_b=x$ , the lifeguard should run across the shore a distance of 48.074 m before jumpng into the water in order to minimize the time to reach the child.

7 0

3 years ago

Costs $17.60 for a pack of 4 padlocks.Find the unit price in dollars per padlock.If necessary, round your answer to the nearest

mel-nik [20]

4=$17.60

1=$17.60/4

1=$4.40

Hole this helps :)

6 0

3 years ago

A store has 1173 pairs of socks. the socks are sold in packs of 4 pairs. how many packs of socks can the store sell?

Nadusha1986 [10]

Answer:

293 packs is the maximum the store can sell.

Step-by-step explanation:

Determine the number of packs that can be made with 4 pairs of socks.

(1173 pairs)/(4 pairs/pack) = 293.25 packs

We can't sell 0.25 pack (1 pair of socks), so drop that fraction to yield 293 full packs. Donate the spare pair, so to speak, to the local IRS agent.

5 0

2 years ago

Which transformation can verify congruence by turning one triangle 90 degrees

Nezavi [6.7K]

The answer to the question of yours is A. Rotation Its not B. because the question is asking by turning one triangle 90 degrees. This would mean that B. is incorrect since its turning. It wouldn't be C. because it isn't translating 90 degrees left or right its turning. And it most definitely wouldn't be D. Dilation because the triangle isn't decreasing or enlarging. Hope this helped feel free to ask any more questions.

6 0

3 years ago

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