Tropical Tours is considering an expansion of its operations, which will require the company to issue new debt and equity. Tropical’s investment banker provided the following information about the cost of issuing new debt:

Amount of Debt Issued                     Yield to Maturity, rd
$1 – $450,000 .......................................            4.5%
450,001 – 750,000 ................................            5.8
Over 750,000.........................................             6.5

If Tropical’s capital structure consists of 60 percent debt, what WACC break points are associated with issuing new debt?