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3 years ago

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Element X is a radioactive isotope such that every 25 years, its mass decreases by half. Given that the initial mass of a sample

of Element X is 50 grams, how much of the element would remain after 23 years, to the nearest whole number?

1 answer:

Julli [10]3 years ago

7 0

50*(.5)^(23/25)=26.43

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The weekly earnings of students in one age group are normally distributed with a standard deviation of 47 dollars. A researcher

ELEN [110]

Answer:

Option D) 340

Step-by-step explanation:

We are given the following in the question:

Alpha, α = 0.05

Population standard deviation, σ = $47

Margin of error = 5

95% Confidence Interval:

$\mu \pm z_{critical}\frac{\sigma}{\sqrt{n}}$

$\text{Margin of error} = z_{critical}\frac{\sigma}{\sqrt{n}}$

Putting the values, we get,

$z_{critical}\text{ at}~\alpha_{0.05} = 1.96$

$5 = 1.96(\dfrac{47}{\sqrt{n}} )\\\\\sqrt{n} = \dfrac{47\times 1.96}{5}\\\\n = 339.443776\\\Rightarrow n \approx 340$

Thus, the correct answer is

Option D) 340

7 0

3 years ago

Help! This is due today and I'm stuck on this problem.

Varvara68 [4.7K]

Answer:

280.6 $m^2$

Step-by-step explanation:

<u>find the length of each side:</u>

you're only given h = 9 m

the formula for h is $h=\frac{\sqrt{3} }{2} *a$ , where a is a side length of the hexagon

plug h in:

$9=\frac{\sqrt{3}}{2}*a\\\\a=9*\frac{2}{\sqrt{3}}\\\\$

a ≈ 10.392 m

<u>now find the area of a triangle:</u>

1/2 (10.392)(9) = 46.764 $m^2$

multiply that by 6 and you get 280.584 ≈ 280.6 $m^2$

you can also use the regular hexagon area formula instead of finding the individual area and multiplying by 6: $\frac{3\sqrt{3} }{2} *a^2$

7 0

3 years ago

Read 2 more answers

1) A boat traveled 448 miles downstream and back. The trip downstream took 14 hours. The trip

Serhud [2]

Answer:B

I think we are in the same class lol

Step-by-step explanation:448 divided by 14= 32

448 divided by 16= 28

B=speed of boat in water

Y= Speed of current

B+y=32

B-y=28

32 + 28 =60

60 divided by 2 = 30

32 -30 =2

B=30

Y=2

Add my discord if you need more help Snapple#0141

6 0

3 years ago

The cost (in dollars) of a custom made sweatshirt is represented by 3.5n +29.99, where n is the number of different colors in th

juin [17]

Answer:

$52.5n+449.85$

Step-by-step explanation:

The cost is given for <em>1 sweatshirt</em>. To find the cost of 15 sweatshirts, we need to multiply the expression by 15. Let's do this:

$15(3.5n+29.99)\\=15(3.5n+29.99)\\=15(3.5n)+15(29.99)\\=52.5n+449.85$

This is the expression that represents the cost of 15 sweatshirts.

8 0

3 years ago

It's all on the picture please answer it

zubka84 [21]

14?
17-12=5
5x2=10
10+4 =14

7 0

3 years ago

Read 2 more answers