SELF DOUBT

Question

https://gateoverflow.in/3561/gate2006-it-22

ANYONE HELP WITH THE LITTLE EASY APPROACH ?

Comments

it is already simplified.... if you didn't get it, go step by step

let E= ( 1×(p) ) + ( 2×(1−p)(p) ) + ( 3×(1−p)(1−p)(p) )+…      =======> (1)

multiply both side with (1−p) and subtract:

multiply both side with (1-p) =======> (2)

subtract (1) and (2)