A sample of a radioactive isotope had an initial mass of 620 mg in the year 2003 and decays exponentially over time. A measurement in the year 2005 found that the
sample's mass had decayed to 390 mg. What would be the expected mass of the
sample in the year 2010, to the nearest whole number?

translate k to n and reflect across the line containing jk.

step-by-step explanation: it is d

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places

16.80 times .20= 3.36

step-by-step explanation: