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he half-life of a certain radioactive substance is 14 days. There are 6.6 grams of the substance present initially. Which equation represents the number of grams of the radioactive substance on day 42 ?

he half-life of a certain radioactive substance is 14 days. There are 6.6 grams of-example-1

2 Answers

6 votes

Answer:

First one

Explanation:

The first one

y = 6.6 (1/2 ) ^n where n = the number of half lives

42 days/ 14 days/halflife = 3 halflives

User Arun Joseph
by
8.1k points
3 votes

Answer:


y=6.6(0.5)^3

Explanation:

half-life of 14 days, basically means it reduces by 50% or half every 14 days.

This can generally be expressed as:
f(x)=a(0.5)^{(t)/(h)}, where h=half life, and t=time, where the unit of time for t and half-life is the same. also a is the initial value.

So we can express this half-life equation as:
f(x)=6.6(0.5)^{(t)/(14)} where t=days.

So plugging in 42 days in here, we get:
f(x)=6.6(0.5)^{(t)/(14)} = 6.6(0.5)^3

The reason for this is because 42 days is 3 half-lives.

User Danielhadar
by
7.1k points

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