Assuming that radiation with \lambda = 15.0 {\rm cm} is used, that all the energy is converted to heat, and that 4.184 {\rm J} is needed to raise the...

Assuming that radiation with lambda = 15.0 {rm cm} is used, that all the energy is converted to heat, and that 4.184 {rm J} is needed to raise the temperature of 1.00 {rm g} of water by 1.00 ^circ {rm C}, how many photons are necessary to raise the temperature of a 350 mL cup of water from 25^circ C to 95^circ C?