A 10 cd point source lamp and a 60 cd point....

Question

this looks simple but how do u solve it???

A 10 cd point source lamp and a 60 cd point source lamp cast equal intensities on a wall. If the 10 cd lamp is 4.0 m from the wall, how far is the 60 cd lamp?

m

Answer 1

10cd=60cd

4m=?m  cross multiply

60*4=10*m  240=10m

m=24m.So the 60cd is 24m from the wall