Answer:
The answer is
<h2>9/100</h2>
Step-by-step explanation:
11.5/128
First convert the decimal to an improper fraction
That's

So we have

Change the division sign to multiplication sign and reverse the second number
That's

Simplify

Divide through by 32
The final answer is

Hope this helps you
Answer:

Step-by-step explanation:
Given


Required

We have:

This gives:

Open bracket

Collect like terms


Answer:
Step-by-step explanation:
For a first order decay, fraction remaining = 0.5n where n = number of half lives elapsed.
fraction remaining = 55% = 0.55
0.55 = 0.5n
log 0.55 = n log 0.5
-0.2596 = -0.301 n
n = 0.8625 = # of half lives elapsed
0.8625 half lives x 2.5 billion years/half live = 2.16 billion years have elapsed = age of the rock
b) 0.15 = 0.5n
log 0.15 = n log 0.5
-0.824 = -0.301 n
n = 2.74 half lives
2.5 billion years/half life x 2.74 half lives = 6.85 billion years = age of rock