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2 years ago

I REALLY NEED HELP BESTAY :,)

Mathematics

1 answer:

dexar [7]2 years ago

8 0

Answer:

1 is the answer

Step-by-step explanation:

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At a store customers are randomly selected to participate in the survey on Friday there were 500 customers at the store. of thos

Artemon [7]

The probability is 90/500 =18%

700*18%= 700 *18/100 = 126

126 customers will be selected to participate in the survey on Saturday

8 0

3 years ago

Alex skateboards at a constant speed from his house to school 3.8 miles away. It takes him 18 minutes. What fraction represents

Paraphin [41]

Speed is expressed as the ratio of distance/time = d/t

in Alex's case, speed = (3.8 miles / 18 minutes)

. . . or simply

3.8/18

8 0

3 years ago

Mr. Arellano decided to make cookies for 7th grade students. He was supposed to mix 4 cups of flour, 1.2 cups of sugar, and 2.5

Ahat [919]

Answer:

0.6 cups of sugar and 1.25 cups of chocolate chips

Step-by-step explanation:

We can begin to solve this problem with a simple proportion:

$\frac{4}{2}$ = $\frac{1.2}{x}$ = $\frac{2.5}{y}$

(x = the new # of sugar y = new # of chocolate chips)

In order to keep everything proportional, we must abide by the scale factor shown with the the flour.

Basically, if we're going to use three times the amount of flour we actually need, then we need to triple all our other ingredients.

We can see that the scale factor is one half, so

x = 1.2 * 0.5

and

y = 2.5 * 0.5

This means that:

x = 0.6

y = 1.25

This means that he has to use 0.6 (or 3/5) cups of sugar and 1.25 (or 9/8) cups of chocolate chips.

8 0

3 years ago

A tank contains 10 liters of pure water. Saline solution with a variable concentration 5 grams of salt per liter is pumped into

algol [13]

Answer:

dQ(t)/dt = 20 - 2Q(t)/5 , Q(0) = 0

Step-by-step explanation:

The mass flow rate dQ(t)/dt = mass flowing in - mass flowing out

Since 5 g/L of salt is pumped in at a rate of 4 L/min, the mass flow in is thus 5 g/L × 4 L/min = 20 g/min.

Let Q(t) be the mass present at any time, t. The concentration at any time ,t is thus Q(t)/volume = Q(t)/10. Since water drains at a rate of 4 L/min, the mass flow out is thus, Q(t)/10 g/L × 4 L/min = 2Q(t)/5 g/min.

So, dQ(t)/dt = mass flowing in - mass flowing out

dQ(t)/dt = 20 g/min - 2Q(t)/5 g/min

Since the salt just begins to be pumped in, the initial mass of salt in the tank is zero. So Q(0) = 0

So, the initial value problem is thus

dQ(t)/dt = 20 - 2Q(t)/5 , Q(0) = 0

3 0

2 years ago

Among all pairs of numbers with a sum of 238238, find the pair whose product is maximum. Write your answers as fractions reduced

mylen [45]

Answer:

$x=119119,\;\;\;y=119119$

Step-by-step explanation:

Let the $x$ be the first number, $y$ be the second number and $p$ be the product of the first and second number.

i.e $x+y=238238$ $\Rightarrow x=238238-y$

$p=xy$

$\Rightarrow p=(238238-y)y\\\Rightarrow p=238238y-y^2$

$\Rightarrow \frac{dp}{dy} =238238-2y\\\Rightarrow 0=238238-2y\\\Rightarrow 2y=238238\\\Rightarrow y=119119$

Now,

$x=238238-119119\\\\ \Rightarrow x=119119$

Hence, $x=119119,\;\;\;y=119119$

8 0

2 years ago