Answer:
3/16 or 0.1875
Step-by-step explanation:
Since she remembers the first two digits, she only has to guess the last two digits. If both digits are greater than 5, there are 4 possible alternatives for each digit (6, 7, 8 or 9).
In three tries, the probability that she will get it right is:
The probability she will get access to her account is 3/16 or 0.1875.
Answer:
Given that,
The number of grams A of a certain radioactive substance present at time, in years
from the present, t is given by the formula
a) To find the initial amount of this substance
At t=0, we get
We know that e^0=1 ( anything to the power zero is 1)
we get,
The initial amount of the substance is 45 grams
b)To find thehalf-life of this substance
To find t when the substance becames half the amount.
A=45/2
Substitute this we get,
Taking natural logarithm on both sides we get,
Half-life of this substance is 154.02
c) To find the amount of substance will be present around in 2500 years
Put t=2500
we get,
The amount of substance will be present around in 2500 years is 0.000585 grams