I am reading this quote "There is an inverse relation between TCP throughput and single link propagation delay . Numerical example : At 4 kbps bandwidth : If propagation delay is 0.25 sec , throughput is 2.4 , but if propagation delay increases to 2.25 sec , throughput drops down to 1 . Further , if propagation delay increases to 3.5 sec , throughput becomes 0.8 ."

I am wondering what formula that may have been used to obtain a value for throughput by using bandwiith and propagation delay.