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3 years ago

155% of what number is 43.4?

Mathematics

2 answers:

Fed [463]3 years ago

7 0

67.27

155 = 1.55 x 43.4 = 67.27

jeyben [28]3 years ago

4 0

Answer:

280

Step-by-step explanation:

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(Brainliest to the person that get its right)

oksian1 [2.3K]

<h3>Answer: Choice B</h3>

c^2-2cd+d^2 = (c-d)^2

We can verify this with the following steps

(c-d)^2 = (c-d)(c-d)

(c-d)^2 = c(c-d) - d(c-d)

(c-d)^2 = c^2-cd-cd+d^2

(c-d)^2 = c^2-2cd+d^2

6 0

2 years ago

The core melt- down and explosions at the nuclear reactor in Chernobyl in 1986 released large amounts of strontium-90, which dec

elena-14-01-66 [18.8K]

If $S(t)$ is the amount of strontium-90 present in the area in year $t$ , and it decays at a rate of 2.5% per year, then

$S(t+1)=(1-0.025)S(t)=0.975S(t)$

Let $S(0)=s$ be the starting amount immediately after the nuclear reactor explodes. Then

$S(t+1)=0.975S(t)=0.975^2S(t-1)=0.975^3S(t-2)=\cdots=0.975^{t+1}S(0)$

or simply

$S(t)=0.975^ts$

So that after 50 years, the amount of strontium-90 that remains is approximately

$S(50)=0.975^{50}s\approx0.282s$

or about 28% of the original amount.

We can confirm this another way; recall the exponential decay formula,

$S(t)=se^{kt}$

where $t$ is measured in years. We're told that 2.5% of the starting amount $s$ decays after 1 year, so that

$0.975s=se^k\implies k=\ln0.975$

Then after 50 years, we have

$S(50)=se^{50k}\approx0.282s$

5 0

3 years ago

The brand manager for a brand of toothpaste must plan a campaign designed to increase brand recognition. He wants to first deter

VMariaS [17]

Answer:

He must survey 123 adults.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the z-score that has a p-value of $1 - \frac{\alpha}{2}$ .

The margin of error is:

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

Assume that a recent survey suggests that about 87% of adults have heard of the brand.

This means that $\pi = 0.87$

90% confidence level

So $\alpha = 0.1$ , z is the value of Z that has a p-value of $1 - \frac{0.1}{2} = 0.95$ , so $Z = 1.645$ .

How many adults must he survey in order to be 90% confident that his estimate is within five percentage points of the true population percentage?

This is n for which M = 0.05. So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.05 = 1.645\sqrt{\frac{0.87*0.13}{n}}$

$0.05\sqrt{n} = 1.645\sqrt{0.87*0.13}$

$\sqrt{n} = \frac{1.645\sqrt{0.87*0.13}}{0.05}$

$(\sqrt{n})^2 = (\frac{1.645\sqrt{0.87*0.13}}{0.05})^2$

$n = 122.4$

Rounding up:

He must survey 123 adults.

6 0

3 years ago

What is the prime factorization of 81 m^2x^3 ?

kondaur [170]

The prime factorisation of 81 is 3^4(because 3*3*3*3 four times =81)
do not change the rest 3^4 m^2 x^3

5 0

3 years ago

Many has 48 feet of wood he wants to use all of it to create a border around a garden. The equation 2l+2w=48 can be used to find

lord [1]

2L + 2W = 48

L= 15 feet

substitute the given value to the formula provided.

2(15) + 2W = 48

multiply 2 by 15

30 + 2W = 48

use the subtraction property of equality to cancel the value 30 on the left side.

30 - 30 + 2W = 48 - 30

cancel 30 on the left side leaving 2W while subtract 30 from 48.

2W = 18

divide both sides to get the value of the width.

2W/2 = 18/2

W = 9ft this is the final answer.

5 0

3 years ago

155​% of what number is 43.4​?

155% of what number is 43.4?