Answer:
b.
Step-by-step explanation:
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:
Then, the time (speed divided by distance) is:
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\\\\](https://tex.z-dn.net/?f=%5Cdfrac%7Bdt%7D%7Bdx%7D%3D%5Cdfrac%7B1%7D%7B4%7D%2B%5Cdfrac%7B1%7D%7B1.1%7D%28%5Cdfrac%7B1%7D%7B2%7D%29%5Cdfrac%7B2x-120%7D%7B%5Csqrt%7Bx%5E2-120x%2B5200%7D%7D%20%5C%5C%5C%5C%5C%5C%5Cdfrac%7Bdt%7D%7Bdx%7D%3D%5Cdfrac%7B1%7D%7B4%7D%20%2B%5Cdfrac%7B1%7D%7B1.1%7D%20%5Cdfrac%7Bx-60%7D%7B%5Csqrt%7Bx%5E2-120x%2B5200%7D%7D%20%3D0%5C%5C%5C%5C%5C%5C%20%20%5Cdfrac%7Bx-60%7D%7B%5Csqrt%7Bx%5E2-120x%2B5200%7D%7D%20%3D%5Cdfrac%7B1.1%7D%7B4%7D%3D%5Cdfrac%7B2%7D%7B7%7D%5C%5C%5C%5C%5C%5C%20x-60%3D%5Cdfrac%7B2%7D%7B7%7D%5Csqrt%7Bx%5E2-120x%2B5200%7D%5C%5C%5C%5C%5C%5C%28x-60%29%5E2%3D%5Cdfrac%7B2%5E2%7D%7B7%5E2%7D%28x%5E2-120x%2B5200%29%5C%5C%5C%5C%5C%5C%28x-60%29%5E2%3D%5Cdfrac%7B4%7D%7B49%7D%5B%28x-60%29%5E2%2B40%5E2%5D%5C%5C%5C%5C%5C%5C%281-4%2F49%29%28x-60%29%5E2%3D4%2A40%5E2%2F49%3D6400%2F49%5C%5C%5C%5C%2845%2F49%29%28x-60%29%5E2%3D6400%2F49%5C%5C%5C%5C45%28x-60%29%5E2%3D6400%5C%5C%5C%5C)
As 
, 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.
Answer:
Table 1 and 2 represent a function
Step-by-step explanation:
Given
<em>Table 1</em>
x 5 10 11
y 3 9 15
<em></em>
<em>Table 2</em>
x 5 10 11
y 3 9 9
<em>Table 3</em>
x 5 10 10
y 3 9 15
Required
Determine which of the tables represent that y is a function of x
For a relation to be a function; the x values must be unique.
In other words, each x value must not be repeated;
Having said that;
Analyzing Table 1
<em>Table 1</em>
x 5 10 11
y 3 9 15
<em></em>
Note that the x rows are unique as no value were repeated;
Hence, Table 1 is a function
<em>Table 2</em>
x 5 10 11
y 3 9 9
Note that the x rows are unique as no value were repeated;
Hence, Table 2 is a function
<em>Table 3</em>
x 5 10 10
y 3 9 15
Note that the x rows are not unique because 10 was repeated twice;
Hence, Table 3 is not a function
Answer:
Option 1 looks most suitable
Step-by-step explanation:
Check image below:
Brainliest please
Hello! $800 was the past amount for rent and now it's $900. 900 - 800 is 100. that's a $100 difference. In order to find the percent increase in the rent, we can write and sovle a proportion. It would be set up as change/original = x/100, where change is difference between two numbers and original is the previous price. It would be set up like this:
100/800 = x/100
Let's crossmultiply the values. 100 * 100 is 10,000. 800 * x is 800x. That makes 10,000 = 800x. Now, divide each side by 800 to isolate the x. 800x/800 cancels out. 10,000/800 is 12.5 or 12.5%. Let's check this by multiplying by 112.5%. 800 * 112.5% (1.125) is 900. That's what we're looking for! There. x = 12.5%. The percent increase is 12.5%.
