Desmos Graphing Calculator

CalcReferenceCopy

Math·Advanced Math·Nonlinear functions

medium

An exponential function $f$ gives the estimated amount of an X-ray beam’s initial intensity remaining after passing through a $w$-centimeter-thick window made of beryllium. The function estimates that after passing through a $1.8$-centimeter-thick window, the amount of the X-ray beam’s initial intensity remaining is $0.65$. Which equation could define $f$?

A

$f(w)=0.65(0.78{)}^{w-1.8}$

B

$f(w)=0.65(0.78{)}^{\frac{w}{1.8}}$

C

$f(w)=0.65(1.8{)}^w$

D

$f(w)=1.8(0.65{)}^w$