Leyla drops a penny from a height of 150m.

Pamela Is 10 years older than Jiri. The sum of their ages is 96. What is Jiri’s age

Solnce55 [7]

43 is jiri and 53 is pamela

8 0

4 years ago

Read 2 more answers

Find<br> ∫^[infinity]_-[infinity] x/(1+x^2)^2 dx.

son4ous [18]

Answer:

Step-by-step explanation:

integral(x/(1+x^2)^2)dx

=(1/2)integral(2x/(1+x^2)^2)dx

=(1/2)[-1/(1+x^2)] +c

3 0

3 years ago

You are fundraising for the schools track team by selling clothing. The first day, you sell 13 t-shirts and 17 pairs of shorts f

Anastasy [175]

Answers:

one t-shirt costs $10

one pair of shorts costs $15

============================================================

Explanation:

x = cost of one t-shirt

y = cost of one pair of shorts

13x+17y = 385 is the first equation because 13x represents the money you get from selling 13 shirts, and the 17y represents the amount you get from selling 17 shorts. The total 13x+17y is given to be $385

The second equation is 13x+12y = 310 for similar reasoning, but this time you sell 12 shorts this time and you get $310 in revenue.

The system of equations we have is:

$\begin{cases}13x+17y = 385\\13x+12y=310\end{cases}$

There are a few ways to solve this system. Possibly the quickest method is to note that the 13x shows up twice, so we can subtract straight down to eliminate the x terms

So,

13x-13x becomes 0x or just 0, and the x terms go away.
17y-12y becomes 5y
385-310 becomes 75

After those three subtractions, we have the equation 5y = 75 which solves to y = 15 after dividing both sides by 5. This means the cost of one pair of shorts is $15

Plug this y value into any equation involving x and y, and solve for x

13x+17y = 385

13x+17(15) = 385

13x+255 = 385

13x = 385-255

13x = 130

x = 130/13

x = 10

Therefore, each t-shirt costs $10

-----------------

To help verify the answer, plug (x,y) = (10,15) into each equation. We should end up with a true result after simplifying both sides.

Start with the first equation

13x+17y = 385

13(10)+17(15) = 385

130+255 = 385

385 = 385

We get a true result which confirms the first equation.

Repeat for the second equation.

13x+12y = 310

13(10)+12(15) = 310

130+180 = 310

310 = 310

Both equations are true so (x,y) = (10, 15) has been fully confirmed.

6 0

3 years ago

What’s the missing factors for these questions?

dem82 [27]

The answer to your question is 57.6

6 0

3 years ago

Of 585 samples of seafood purchased from various kinds of food stores in different regions of a country and genetically compared

Dafna1 [17]

Answer:

a) The 99% confidence interval is from 14.8% to 23.2%.

b) The confidence interval tells us that the true proportion of mislabeled is within 14.8% and 23.2%, with a 99% confidence. In other words, if we take samples of the same size, 99% of the samples will have a proportion within 0.148 and 0.232.

c) The confidence interval calculation take into account the sample size, so the width (or precision) of the interval depends on the sample size.

The only criticism that could be analyzed is to see if the sample is representative of the population.

Step-by-step explanation:

a) We have to calculate a 99% confidence interval for the proportion.

The sample proportion is p=0.19.

The standard error of the proportion is:

$\sigma_p=\sqrt{\dfrac{p(1-p)}{n}}=\sqrt{\dfrac{0.19*0.81}{585}}\\\\\\ \sigma_p=\sqrt{0.000263}=0.016$

The critical z-value for a 99% confidence interval is z=2.576.

The margin of error (MOE) can be calculated as:

$MOE=z\cdot \sigma_p=2.576 \cdot 0.02=0.042$

Then, the lower and upper bounds of the confidence interval are:

$LL=p-z \cdot \sigma_p = 0.19-0.042=0.148\\\\UL=p+z \cdot \sigma_p = 0.19+0.042=0.232$

The 99% confidence interval for the population proportion is (0.148, 0.232).

5 0

3 years ago