The effective resistance of three resistors connected in parallel is 60/47 Ω. When one wire breaks, the effective resistance becomes 15/8 ohms. Find the resistance of the wire that is broken.

As the three resistors are in parallel combination to each other , so , let the total resistance of the 3 resistors be R₃ and the total resistance of the two resistors be R₂ ,

Let the three resistors be R_a , R_b , R_c .

First we will calculate the total resistance of 3 resistors,

We are given with the values of R₃ = 60/47 ohm and R₂ = 15/8 ohms ,

When one wire is broken down , let the wire be of resistance R_a , so

Put the value of two resistor equation in three resistor equation ,

We get ,

Hence this is the required resistance.