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3 years ago

I need help on this question

Mathematics

1 answer:

xxMikexx [17]3 years ago

4 0

I think it’s B but I’m not 100%

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ale4655 [162]

t = 2/3. Multiply the numbers in the parentheses by -1. It becomes 9t + -3t + -3 = 1. Combine like terms to get 6t + -3 = 1. Add 3 to both sides to get 6t = 4. Divide both sides by 6. t = 2/3

3 0

3 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

Birth Weights Babies born after a gestation period of 32-35 weeks have a mean weight of 2600 grams and a standard deviation of 6

lukranit [14]

Answer:

The z-score for the 34-week gestation period baby is 0.61

Step-by-step explanation:

The formula for calculating a z-score is is z = (x-μ)/σ,

where x is the raw score,

μ is the population mean

σ is the population standard deviation.

We are told in the question that:

Babies born after a gestation period of 32-35 weeks have a mean weight of 2600 grams and a standard deviation of 660 grams. Also, we are supposing a 34-week gestation period baby weighs 3000grams

The z-score for the 34-week gestation period baby is calculated as:

z = (x-μ)/σ

x = 3000, μ = 2600 σ = 660

z = 3000 - 2600/660

= 400/660

=0.6060606061

Approximately, ≈ 0.61

6 0

3 years ago

Timothy stated that the sum of 0.9 + (-9/10) was 18/20.

Evgesh-ka [11]

Answer:

18/10

Step-by-step explanation:

3 0

3 years ago

Read 2 more answers

Inessa [10]

Answer:

Approximately 920.324 p/m

Step-by-step explanation:

so to figure this out, we need to simply divide 6,688 people by 7.267 square miles. 6,688/7.267=920.324.... So we have approximately 920.324 people per square mile

5 0

3 years ago