What is the formula for calculation of Mean Holding Time?

The Mean Holding Time (MHT) can be calculated using the formula:

[ \text{MHT} = \frac{\sum (t_i \times n_i)}{\sum n_i} ]

where ( t_i ) represents the time held for each item, and ( n_i ) is the number of items held for that time. Essentially, MHT is the weighted average of holding times, taking into account the frequency of each holding time.