Since magnification is 0.0156, I have:
m = -i/o
0.0156 = -24cm/o
o = -1538.46 cm
1/f = 1/i + 1/o
1/f = 1/24 cm - 1/1538.36 cm
f = 24.38 cm
R = 48.76 cm
However, when I look up the average corneal radius, the google results show ~5 mm. Did I do something wrong?