Let's see if you can correctly use a calculator.
There are two points in the Zapruder film that can be identified as times shots were fired.
1. Zapruder frame 313, the time that a shot hit President Kennedy in the head.
2. Zapruder frame 224, the time that we first see John Connally BEGIN to react to a shot. It has been said that Connally's jacket bulges out at that point (you can see that is true IF you have a decent set of digital frames available to review).
The film speed of Zapruder's camera was measured as 18.3 frames per second. To calculate the time between events in the Zapruder film you simply divide the number of film frames by 18.3
Time between Z frames 313 and 224 = (313 - 224)/18.3 = 4.8 seconds
There is a second way to determine the time between shots. That information has been viciously attacked as invalid but before you make a FINAL judgement, look at the figure below. The time between shots #3 and #4 is 4.8 seconds!
The FACT that there is 4.8 seconds between shots in the Zapruder film and 4.8 seconds between shots from the acoustical study of the only audio recording is NOT sufficient to PROVE that the audio recording did capture the sounds of the shots BUT it is a fact that was never mentioned in Vince Bugliosi's RECLAIMING HISTORY nor has it been mentioned very many times before (except by me of course because I understand the significance of that information). No, to prove that the audio evidence is valid (i.e. the sounds of the shots were recorded on the Dallas police radio channel) you have to show more than one match in both the Z film and the audio recording. That would take a few more minutes of typing to show the next match and you probably wouldn't understand it and even if you do, you probably won't believe it.
Utter crap OR have Americans been made into the biggest set of fools in history? The correct answer is fools.