I’m learning this too.. so what you do it see what will the number he if it was a while line so to find that out you will add 7+7 and get 14 so that’s the whole
So 7 x 7 will equal 49 and 49 x 3.14 will give you 153.86 as the answer

5 0

3 years ago

A tank contains 3000 L of pure water. Brine that contains 15 g of salt per liter of water is pumped into the tank at a rate of 2

max2010maxim [7]

Answer:

15 g/L

Step-by-step explanation:

Since Brine is added to the tank containing 15g/L at a rate of 25 L/min, the rate at which the quantity of salt in the tank increases is 15 g/L × 25 L/min = 375 g/min. So, in t minutes, the mass of salt in the tank, m is 375 g/min × t min = 375t

Also, the volume of the tank increases by 25 L/min, in t minutes, its volume increases by 25 L/min × t min = 25t. So, the new volume, V is 3000 + 25t.

Since we know, concentration C(t) = m/V = 375t/(3000 + 25t)

dividing through by 25, we have

C(t) = 375t/25/(3000/25 + 25t/25)

C(t) = 15t/(120 + t)

To find the limit as t ⇒ ∞, we divide C(t) by t

C(t) = 15t/t/(120/t + 1)

C(t) = 15/(120/t + 1)

putting t = ∞, we have

C(∞) = 15/(120/∞ + 1)

C(∞) = 15/(0 + 1)

C(∞) = 15/1

C(∞) = 15 g/L

So, as t t → [infinity], the concentration approaches 15 g/L

3 0

3 years ago

A hiker is climbing down a valley. He stops for a water break 4 times. Between each break, he descends 15 meters. How many meter

Murljashka [212]

The word in the problem that indicates that a negative sign should be used is "descend"

<h3></h3><h3>How many meters did he descend?</h3>

We know that he stops for water breaks four times, and between each water break, he descends 15 meters.

The written equation is:

4*(-15)m = -60m

Why the negative sign is used?

The negative sign is used because the hiker is descending, so its height is decreasing. The word in the problem that indicates that a negative sign should be used is "descend"

If you want to learn more about signs:

brainly.com/question/5870782

#SPJ1

7 0

2 years ago