A Meterstick Is Supported by a Knife-Edge at the 50-Cm

Multiple Choice

A meterstick is supported by a knife-edge at the 50-cm mark.Doug hangs masses of 0.40 and 0.80 kg from the 15-cm and 80-cm marks,respectively.Where should Doug hang a third mass of 0.20 kg to keep the stick balanced?

A) 100 cm
B) 10 cm
C) 90 cm
D) 0 cm
E) 50 cm