33s^5t^4u^8 ÷ 11st^3u^8

Carbon–14 is a radioactive isotope that decays exponentially at a rate of 0.0124 percent a year. How many years will it take for

stepan [7]

The decay rate should have units, it should be negative and it should be 100 times smaller than what you posted.
k = -.000124 / years

k = -.000124 / years
Half-Life = ln (.5) / k
Half-Life = -.693147 / -.000124
Half-Life = 5589.8951612903 
Half-Life = 5,590 (rounded)

elapsed time = half-life * log(bgng amt / end amt) / log(2)
elapsed time = 5,590 * log(10) / 0.3010299957 
elapsed time = 5,590 * 1 / 0.3010299957 
elapsed time = 18,569 years

Source:
http://www.1728.org/halflife.htm

5 0

2 years ago

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A supervised learning model has been built to predict whether someone is infected with a new strain of a virus. The probability

larisa [96]

Answer:

A baseline score of 99% needs to be set.

Step-by-step explanation:

Since this is an example of a classification problem (the classes being whether somebody has been infected with a new virus or not), the ideal score to achieve in such a case is 100%. Hence, a baseline score of 99% should be set in order to get to 100% by outperforming it.

7 0

2 years ago

From generation to generation, the mean age when smokers first start to smoke varies. However, the standard deviation of that ag

Jlenok [28]

Answer:

If we compare the p value and the significance level given for example $\alpha=0.05$ we see that $p_v$ so we can conclude that we to reject the null hypothesis, and the the actual mean starting age of smokers is significantly lower than 19.

Step-by-step explanation:

1) Data given and notation

$\bar X=18.1$ represent the mean age when smokers first start to smoke varies

$s=1.3$ represent the standard deviation for the sample

$\sigma=2.1$ represent the population standard deviation

$n=37$ sample size

$\mu_o =5.7$ represent the value that we want to test

$\alpha$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to determine if the mean starting age is at least 19, the system of hypothesis would be:

Null hypothesis: $\mu\geq 19$

Alternative hypothesis: $\mu < 19$

We know the population deviation, so for this case is better apply a z test to compare the actual mean to the reference value, and the statistic is given by:

$z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}$ (1)

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$z=\frac{18.1-19}{\frac{2.1}{\sqrt{37}}}=-2.607$

Calculate the P-value

Since is a one-side lower test the p value would be:

$p_v =P(z$

Conclusion

If we compare the p value and the significance level given for example $\alpha=0.05$ we see that $p_v$ so we can conclude that we to reject the null hypothesis, and the the actual mean starting age of smokers is significantly lower than 19.

4 0

2 years ago

Which oh the following are among the five basic postulates of Euclidean geometry

igomit [66]

1. A straight line segment can be drawn joining any two points.

2. Any straight line segment can be extended indefinitely in a straight line.

3. Given any straight line segment, a circle can be drawn having the segment as radius and one endpoint as center.

4. All right angles are congruent.

5. If two lines are drawn which intersect a third in such a way that the sum of the inner angles on one side is less than two right angles, then the two lines inevitably must intersect each other on that side if extended far enough. This postulate is equivalent to what is known as the parallel postulate.

8 0

1 year ago

What is the length of Line segment A B? Round to the nearest tenth. Triangle A B C is shown. Angle A C B is a right angle and an

amm1812

C=90°, A=75°, b=AC=19, x=AB

Without a figure, we see AC is adjacent to angle A, so

cos A = AC/AB = b/x

x = b/cos A = 10 / cos 75° ≈ 38.637

Answer: 38.6

3 0

1 year ago

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