Present worth is Rs. 800 and true discount is Rs. 36. Find the banker's discount.

Given data

• PW = Rs. 800
• TD = Rs. 36
• BD = ?

Concept/ApproachFirst find banker's gain using BG = TD² / PW, then BD = TD + BG.

Step-by-step calculationBG = 36² / 800 = 1296 / 800 = 1.62BD = 36 + 1.62 = Rs. 37.62

Verification/AlternativeImplied sum due A = PW + TD = 836; check that BD − TD = BG = 1.62 as computed.

Common pitfallsTaking BD = TD; remember BD exceeds TD by the banker's gain.

Final AnswerRs. 37.62