Asample of a radioactive isotope had an initial mass of 690 mg in the year 1997 and decays exponentially over time. a measurement in the year 2001 found that the sample's mass had decayed to 390 mg. what would be the expected mass of the sample in the year 2011, to the nearest whole number?

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step-by-step explanation:

step-by-step explanation:

the ratio of red paint to blue paint is always 9/7. that means that, whatever x's value, (4x+12)/(4x-4) has that same ratio. so, set up an equation and cross-multiply to solve for x:

9/7 = (4x+12)/(4x-4)

9(4x-4) = 7(4x+12)

36x - 36 = 28x + 84

8x - 36 = 84

8x = 120

x = 15

363 square inches

step-by-step explanation:

surface area of a pyramid is b + 1/2ph

b is the area of the base: 11 x 11 = 121

p is the perimeter of the base: 11 + 11 + 11 + 11 = 44

h is the height of the pyramid: 11

121 + 1/2(44)(11)

121 + 242

363

5.762159

step-by-step explanation:

it would be 9 because when it is the nine is over five so that would mean it rounds up to 90 or 9