The equation is:
P ( t ) = A * (1/2 )^(t/h)
If a sample contains 18% of the original amount of Radon - 222 and h = 3.8:
0.18 * A = A * ( 0.5 )^(t/3.8) / : A ( we will divide both sides of the equation by A )
0.18 = ( 0.5 )^(t/3.8)

t / 3.8 = 2.47 ≈ 2.5
t = 3.8 * 2.5 = 9.5
Answer:
The best estimate for the age of the sample is 9.5 days.
Answer:
1519 pens
Step-by-step explanation:
add 9,645 to 18,836 and then subtract that number from 30,000
Answer/Step-by-step explanation:
The ratio of the enlargement to the original = A'E' to AE = A'E':AE = A'E'/AE
AE = 2.5
A'E' = 4
Ratio of the enlargement to the original = 4:2.5 = 1.6:1
To convert to percentage, divide 4 by 2.5 and multiply by 100.



Let the price of the tickets be 'x' and the number of tickets bought is 'y'
When the y inversely proportioned to x, the equation is
y = k/x where k is a constant
We work out the value of k by using the information y = 6 and x = 5
6 = k/5
k = 30
Hence, the maximum number of tickets when the price is $3 is
y = 30/3
y = 10 tickets