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antoniya
2 months ago
14

A scientist needs 10 liters of a 20% acid solution for an experiment, but she has only a 5% solution and a 40% solution. To the

nearest tenth of a liter, about how many liters of the 5% and the 40% solutions should she mix to get the solution she needs? Explain
Mathematics
1 answer:
Inessa [12.5K]2 months ago
8 0
This problem requires mixing 5% and 40% solutions to create 10 liters of 20% concentration. Multiple solutions exist. Assuming all combined volume equals 10L with no waste, let x represent the volume of the 40% solution. Therefore, the 5% solution volume is 10L - x. Applying concentration calculations: 10L × 20% = x × 40% + (10 - x) × 5%. Solving leads to: x = (10L × 15%) / 35% = 4.28L, rounded to 4.3L for the 40% solution. The 5% volume is then 10L - 4.3L = 5.7L.
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(a) For what values of k does the function y = cos(kt) satisfy the differential equation 81y'' = −4y? (Enter your answers as a c
tester [12383]

Answer:

k = \frac{2}{9}, k=\frac{-2}{9}

Step-by-step explanation:

The initial scenario is a specific case of the subsequent one, so we will address the second case first.

Consider y = A\sin(kt) + B\cos(kt). Through the utilization of derivatives and trigonometric function properties, it is determined that

y' = A\cdot k \cos(kt)- B \cdot k \sin(kt) = k (A\cos(kt)-B\sin(kt))

y'' = k(-A\cdot k \sin(kt)-B\cdot k \cos(kt)) = -k^2(y)

The equation is represented as 81y''=-4y. It's important to note that since y'' = -k^2y it leads to the equation

-k^2 81y=-4y,

which signifies that k^2 = \frac{4}{81}. Consequently, k=\pm\frac{2}{9}

It's notable that in this instance, the value of k is independent of A and B. Thus, it applies universally to any values of A and B. The first scenario is included since it corresponds to A=0 and B=1.

5 0
1 month ago
Four hot air balloons each descend 295 feet per minute for 7 minutes. Find the total change in altitude for all 4 balloon
Svet_ta [12734]

Answer: A total descent of 8260 feet occurred for all four balloons.

Step-by-step explanation:

Based on the information provided:

Number of hot air balloons = 4

Minutes of descent = 7

Descent rate per minute = 295 feet

Thus, the overall change in altitude for all four balloons can be calculated as:

295\times 7\times 4\\\\=8260\ feet

Thus, a total descent of 8260 feet was experienced by the four balloons.

7 0
1 month ago
Read 2 more answers
A mail clerk found that the total weight of 155 packages was 815 pounds. if each of the packages weighed either 3 pounds or 8 po
tester [12383]
To solve this problem, you'll need to create two equations:
x + y = 155 (total packages)
3x + 8y = 815 (total weight)
Next, multiply the first equation by 3: 3x + 3y = 465.
Then, subtract the first equation from the second to find that 5y = 350, which means y = 70. Thus, there are 70 packages that weigh 8 pounds. 
3 0
1 month ago
Read 2 more answers
76% is between which of the following two numbers?
AnnZ [12381]

Hi there!

While there are no answer choices provided, here's how you can solve a problem like this.

To find the average of two numbers, you simply sum them up and divide by two!

For instance, to find the midpoint between 1 and 3, you add 1 and 3 to get 4, then divide by 2 which results in 2!

For 100 and 580, adding gives you 680, and dividing by 2 results in 340!

The average between 0.57 and 0.69 involves adding to get 1.26, then dividing by 2 yields 0.63!

Now, with percentages, for 45% and 67%, the addition gives you 112%, and dividing that by 2 will result in 56%!

So, for your answer options, just calculate the total and divide by two to determine which one results in 76%!

I hope this information helps!

5 0
1 month ago
The marked price of an article is Rs.2080. After allowing d% discount and levying
AnnZ [12381]

Answer:

13%

Detailed breakdown:

Information provided:

  • MP = 2080
  • Discount = d%
  • VAT = (d-2)%
  • Cost = 1997.84

Applying the discount:

  • 2080 - d% = 2080*(1 - 0.01d)

Including VAT:

  • 2080*(1 - 0.01d) + (d - 2)%
  • 2080*(1 - 0.01d) * (1 + (d -2)/100)
  • 2080*(1 - 0.01d) * (0.98 + 0.01d) = 1997.84
  • (1 - 0.01d)(0.98 + 0.01d) = 1997.84/2080
  • 0.98 + 0.01d - 0.0098d - 0.0001d² = 0.9605
  • - 0.0001d² + 0.0002d + 0.98- 0.9605 = 0
  • 0.0001d²- 0.0002d - 0.0195 = 0
  • d² - 2d + 195 = 0

Solving this quadratic equation yields:

  • d = 15

Therefore

  • VAT rate = 15 - 2 = 13%
7 0
1 month ago
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