Students in a biology class are growing bacteria for a science experiment. Which of the following equations could model the amount of bacteria after x days?
y=8(2)^x
y=50(0.2)^x
y=(1/2)^x
y=25(0.68)^x
y=8(2)^x
y=50(0.2)^x
y=(1/2)^x
y=25(0.68)^x