(3) In the case of a document that is, or was at the time it was produced, part of the records of, or kept for the purposes of, a business, whether or not the business is still in existence, then, where the device or process is or was at that time used for the purposes of the business, it shall be presumed, unless the contrary is proved, that on the occasion in question the device or process did what the party adducing the evidence asserts it to have done.