Answer:
So in scientific form 4000 miles will be equal to 
Step-by-step explanation:
We have given that radius of earth is 4000 miles
4000 miles can be written as 4×1000
We have to written 4000 miles in scientific form
We know that 1000 can be written in scientific form as 
So 
So in scientific form 4000 miles will be equal to 
Answer:
Step-by-step explanation:
They are essentially asking us to solve:

Solving this equation for x tells us that it will take around 80.1 years for the materials in the vault to reduce to 357 pounds.
<h3>
Answer: C) x = 13</h3>
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Work Shown:
We have a right triangle with legs a = 5 and b = 12. The hypotenuse is c = x which is unknown for now.
Use the pythagorean theorem to find x.
a^2 + b^2 = c^2
5^2 + 12^2 = x^2
25 + 144 = x^2
169 = x^2
x^2 = 169
x = sqrt(169) .... apply the square root to both sides
x = 13
I am pretty sure the answer is c