Acandy shop puts 1000 magic candies in a jar. after 10 years, half of the green candies turn red. after another 10 years, half of the remaining green candies turn red. this process continues until all the green candies turn red. how many years does it take for 75% of the candies to turn red (25% of the candies remain green)?

The equation that would best represent the given scenario is,
                            At = (Ao) x (0.5)^(n/10)
where At is the number of candles still green in color, Ao is 1000 and n is the number of years. Substituting the known values from the given,
                            250 = 1000 x (0.5^n/10)
 The value of n from the equation is 20. Therefore, after 20 years, only 25% of the candles are green in color. 

Alpha particles have positive charge, beta particles have negative charge, and answer 4 just doesn’t make sense. thus, you are left with only one possible answer.