Answer:
Percentage of (226Ra) after 900 years is 68%
Step-by-step explanation:
Let P(t) be the amount of (226Ra) present at any time t
Half life of (226 Ra) = 1599 years
If P₀ is initial amount of (226 Ra) then after 1599 years
P(1599)=P₀/2
Decay i amount of radioactive substance is related to time t as

To find value of k

Percentage of radioactive element is:
Amount after 900 years
Answer:

Step-by-step explanation:
Given:
Distance for north side = 7 miles.
Distance for east side = 24 miles.
We need to find the displacement.
Solution:
Figure shows Point A is starting point and AB = 7 miles is North side distance and BC = 24 miles is east side distance and AC is shown as displacement.
Using Pythagoras theorem to find displacement (AC).

Substitute AB = 7 and BC = 24 in above equation.




Therefore, displacement of the car 
Answer:
i think its the 3rd one very sorry if im wrong
Step-by-step explanation: