Two identical loudspenkers are placed on a line at distances `4 m` and `5.1875 m` from a microphone lying on the same line. If the output of each speaker at the microphone be `2 mW`, find the resultant output at the microphone, if the two speakers are connected in series and excited by the same oscillator. What is the output at the place if they are excited by separate indentical oscillators of the same freequency? Velocity of sound `=350 m s^(-1)` and frequency of oscillators `=700 Hz`.