Multiple IRR's practice, discount, conceptual, ask, only

LiquidAssets10

Should I expect questions that require you to calculate multiple IRR's for non-conventional CF's? Schweser doesn't have much practice problems on that, just conceptual questions.

The practice problems in V. 4 (p 33) ask for the multiple IRR's and the discount rate that will equate the NPV's of two projects. Honestly, the only way I know how to do both is through trial and error....is there an actual method?