data = {
{400,1503},
{425,1777},
{450,1809},
{475,1848},
{500,1823},
{525,1889},
{550,1901},
{575,1918},
{600,1914},
{625,1933},
{650,1992},
{675,2012},
{700,1945},
{725,2151},
{750,2169},
{775,2198},
{800,2269},
{825,2220},
{850,2263},
{875,2451},
{900,2600}
}

N@Sqrt[data[[All,2]]]

ListPlot[data,AxesOrigin->{350,0}]