Waves

The wavelength of two waves are 40 and \(42 \mathrm{~cm}\) respectively. If the temperature of the room is \(20^{\circ} \mathrm{C}\) then what will be the number of beats produced per second by these waves. When the speed of sound at \(0^{\circ} \mathrm{C}\) is \(332 \mathrm{~m} / \mathrm{s}\) ?