Find the 6th term of the geometric sequence for which a1=-7 and r=-1/3

i got 142 as my answer

step-by-step explanation:

the correct answer is 5 6 and 7

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

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