UPSEE Solved Model Paper 2

An unknown resistance R1 is connected in series with a resistance of 10 Ω. This combination is connected to one gap of a metre bridge, while a resistance R2 is connected in the other gap. The balance point is at 50 cm. Now, when the 10 Ω resistance is removed, the balance point shifts to 40 cm. The valve of R1 is (in ohms)