Chapter 6 Rational Exponents and Radical Functions - 6.4 Use Inverse Functions - Guided Practice for Examples 1, 2, and 3 - Page 439: 4

$48$ inches

The inverse function in Example $3$ is: $$L=\dfrac{8}{3}R+\dfrac{40}{3}.$$ Calculate $L$ when $R=13$: $$L=\dfrac{8}{3}\cdot 13+\dfrac{40}{3}=\dfrac{104}{3}+\dfrac{40}{3}=\dfrac{144}{3}=48.$$ The band provides $13$ pounds of resistance when it is stretched to $48$ inches.