You want to multiply together the number of possible choices for each digit in the code.
0-9 is ten possible numbers, since repetitions are allowed (example code 2,2,2,2) there are ten possible choices per digit in the code.
10*10*10*10 = 10,000 four digit coded possible
I believe the radius is 5 <span />
If the triangles are similar, then the corresponding ratio of their sides have equal ratios. Through ratio and proportion, we would determine the answer.
5/6 = x/9, where x is the length for side PN
Transposing the equation so that x is on the left side:
x = (5/6)*9
x = 7.5
Answer:
192/2= 96 g after 7h
96/2=48 g after 14h
48/2= 24 g after 21h
<h2>24/2= 12 g after 28h </h2>