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ira [324]
3 years ago
10

A toxic radioactive substance with the density of 4 mg/cm² is detected in the been detected in the ventilating ducts that was us

ed 35 years ago. if the half-life of substances 20 years what is the density of a substance when it was deposited 35 years ago
Mathematics
1 answer:
Kruka [31]3 years ago
8 0
The formula for half-life is:

A = P(0.5)^{t/h}

A is the amount remaining, P is the initial amount, t is the time that has passed, and h is the half-life of the substance.  Plug in the values that you know and solve:

4 = P(0.5)^{35/20} \\ \\ 4 = P(0.5)^{1.75} \\ \\ P = \frac{4}{0.5^{1.75}} \\ \\ P \approx 13.4543426441

Rounded to the nearest whole number, the density of the substance was about 13<span>mg / cm².</span>
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A cylinder and a cone are shown below.
Dmitrij [34]

Answer:

The bases do not have the same area because the volume of the cylinder is not 3 times the volume of the cone, given the same heights.

Step-by-step explanation:

Recall :

V1 = volume of cylinder = πr²h

V2 = volume of a cone = 1/3πr²h

From the diagram, both have height, h of 12

Radius = r

V1 = 2512 in

V2 = 1256 in

From the ratio :

2512 = πr² * 12

1256 = 1/3πr² * 12

12 cancel out as well as r² and π

If the bases have the same area `, then 2512 should be equal to (1256 * 3)

2512 in ≠ 3868 in

5 0
2 years ago
Read 2 more answers
Question 10
Agata [3.3K]

Answer:

A = 21

J = 2A = 42

C= A+5 =26



Step-by-step explanation:

C= christines text messages

J = jims messages

A = ali messages

Jim sent  2 times as many messages as Ali.

J = 2A

Ali sent  5 fewer messages than Christine.

A =C-5

A+5 =C

Christine, Jim, and Ali sent a total of 89 text messages

C+J+A = 89

substitute

C +5= A

A+5 +J+A = 89

combine like terms

2A +5+J = 89

now substitute J = 2A

2A +5+2A = 89

combine like terms

4A +5 = 89

subtract 5 to each side

4A +5-5 = 89-5

4A = 84

divide by 4

A = 21

J = 2A = 42

C= A+5 =26


5 0
3 years ago
Please help me! This is a full assignment I’m struggling on haha! Please answer each question and I’ll give Brainliest to whoeve
Marina86 [1]

Answer:

Step-by-step explanation:

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3 0
2 years ago
Two groups of tourist fly to Japan. It takes the first group 4 hours less than the second to fly
Aleksandr-060686 [28]

Answer:

21

Step-by-step explanation:

think about it this way. if the first group takes 17 hours, and the second group takes 4 hours more than the first group, then how long does the second group take?

5 0
2 years ago
1. What is a real world example when you would have to find the circumference of something? Explain.
nikitadnepr [17]
A ferris wheel
A construction worker whose making a ferris wheel would need to know and measure the circumference.
A theme park manger would need to find the circumference to know if the ferris wheel is too big to go into the park.
Hope that helps!!
4 0
3 years ago
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