P=2 so 81-p is equal to 81-2 which equals 79
Answer:
8978 grams
Step-by-step explanation:
The equation to find the half-life is:
N(t) = amount after the time <em>t</em>
= initial amount of substance
t = time
It is known that after a half-life there will be twice less of a substance than what it intially was. So, we can get a simplified equation that looks like this, in terms of half-lives.
or more simply
= time of the half-life
We know that = 35,912, t = 14,680, and =7,340
Plug these into the equation:
Using a calculator we get:
N(t) = 8978
Therefore, after 14,680 years 8,978 grams of thorium will be left.
Hope this helps!! Ask questions if you need!!
Cosα=x/L
L=x/cosα, we are told that the ladder base is 48 ft from the base of the wall and α=39° so:
L=48/cos39 ft
L≈61.76 ft (to nearest hundredth of a foot)
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