Formulae for Word Problems for exponents

1) For general rate , depreciation problems

Y= i x (1 +/- r)^ᵡ where Y= Dependent variable , final value

i= Initial Value

r= rate of increase or decrease

X = The independent variable

2) For half life problems

Y= i x (1 - 0.5)^t/half life

where Y= Dependent variable , final amount left

i= Initial Value , initial amount

t = Time spent