Which of the following terms refers to the numerical probability of the chances that the true value falls within the range of reliability? mean variability confidence level standard deviation

The term that refers to the numerical probability of the chances that the true value falls within the range of reliability is called confidence level.
Saving that you surveyed a whole population, a 100% confidence level is non-existent in statistics,  — and even then you probably couldn’t be 100 percent sure that your survey wasn’t open to some kind of error or bias.

However, if the workers do outside of what's normally expected, go ahead and tip.