In determining where the preponderance of evidence lies, the jury may consider all the facts and circumstances of the case, the witnesses' manner of testifying, their intelligence, their means and opportunity for knowing the facts to which they testified, the nature of the facts to which they testified, the probability or improbability of their testimony, their interest or want of interest, and their personal credibility so far as the same may legitimately appear from the trial. The jury may also consider the number of the witnesses, though the preponderance is not necessarily with the greater number.