A completely mixed dilute suspension of sand particles having diameters $0.25, \: 0.35, \: 0.40, \: 0.45$ and $0.50 \: mm$ are filled in a transparent glass column of diameter $10 \: cm$ and height $2.50 \: m$. The suspension is allowed to settle without any disturbance. It is observed that all particles of diameter $0.35 \: mm$ settle to the bottom of the column in $30 \: s$. For the same period of $30 \: s$, the percentage removal (round off to integer value) of particles of diameters $0.45$ and $0.50 \: mm$ from the suspension is _________