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3 years ago

9

The half-life of a radioactive kind of tellurium is 25 minutes. If you start with 88 grams of it, how much will be left after 50

minutes?

1 answer:

LUCKY_DIMON [66]3 years ago

5 0

Notice that 50 minutes is twice the half-life.

After 25 minutes, half of the starting amount remains, so that 88g decays to 44g.

After another 25 minutes (a total of 50 minutes), the 44g will decay to 22g.

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We need a sample size of least 119

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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.

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So $\alpha = 0.05$ , z is the value of Z that has a pvalue of $1 - \frac{0.05}{2} = 0.975$ , so $Z = 1.96$ .

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At least n, in which n is found when $M = 0.09$

We don't know the proportion, so we use $\pi = 0.5$ , which is when we would need the largest sample size.

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Rounding up

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