When two resistances \( R_1 \) and \( R_2 \) connected in series and introduction into the left gap of a meter bridge and a resistance of \( 10 \, \Omega \) is introduced into the right gap, a null point is found at \( 60 \, \text{cm} \) from left side. When \( R_1 \) and \( R_2 \) are connected in parallel and introduced into the left gap, a resistance of \( 3 \, \Omega \) is introduced into the right-gap to get null point at \( 40 \, \text{cm} \) from left end. The product of \( R_1 R_2 \) is _____ \( \Omega^2 \).
