A scientist is testing a new antibiotic on some bacteria she discovers the the antibiotic kills half of the Bactria every hour if she starts with 42000 bacteria what equation can be used to predict the number of bacteria after x hours a). y= 42000(2)^x
b). y=42000(1/2)^x
c). y=42000(1.5)^x
d). y=(42000/2)^x