We have,
Present value = ₹500000, Depreciated value = ₹364500
Rate of depreciation =10% per annum.
Let the depreciation period be of n years. Then,
364500=500000(1−10100)n
⇒36455000=(910)n
⇒7291000=(910)n⇒(910)3=(910)n⇒n=3
Hence, in 3 years the value of the flat will be reduced to ₹364500.