Solve the problem.The function A = Aoe-0.0077x models the amount in pounds of a particular radioactive material stored in a concrete vault, where x is the number of years since the material was put into the vault. If 500 pounds of the material are placed in the vault, how much time will need to pass for only 270 pounds to remain?
A. 160 years
B. 85 years
C. 90 years
D. 80 years
Answer: D
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The maximum length of a certain fish is 21 inches. Each year the difference D, in inches, between its maximum length and its current length L, in inches, decreases by 12%. The initial difference is 19 inches.
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A: Find a formula that gives the length difference D after ?t years.
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B: The length difference is 
. Find a formula that gives its length after t months.
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C: When will the fish reach 17 inches long? Round your answer to two decimal places if necessary.
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What will be an ideal response?
Provide an appropriate response.A surveyor starts at point A on a triangular piece of land and determines angle A and the two sides AB and AC as shown. The two small ponds inhibit the direct measurement of length BC. Help the surveyor by determining the length of BC. 
A. 584.0 ft B. 301.7 ft C. 604.2 ft D. 149.6 ft
Provide an appropriate response.Is it true that in order to multiply a number by a negative power of ten, you must move the decimal point to the left as many places as indicated by the absolute value of the exponent on the ten?
A. True B. False
Verify that the values of the variables listed are solutions of the system of equations.
x = -1, y = 2, z = 4
A. solution B. not a solution