Answer:
6 mph
Step-by-step explanation:
Difference in distance
= 15 - 12
= 3 mi
time taken
= 30 mins
= 1/2 hour
Speed
= 3 ÷ 1/2
= 6 mph
The amount of substance left of a radioactive element of half life,

after a time, t, is given by:

Given that <span>potassium-40 has a half life of approximately 1.25 billion
years.
The number of years it will take for 0.1% of potassium-40 to remain is obtained as follows:

Therefore, </span><span>the maximum age of a fossil that we could date using 40k is
12.5 billion years.</span>
Answer:
yes 40
Step-by-step explanation:
she got it correct