I am just trying to help. I am not sure of the answer. Experts please check my answer. Thank you.
I think the Soft White Bulb has a longer life span,
because its mean, which is an average, is 700, this means that most Sofe White Bulb can last 700 hours, and its standard deviation is 35, which is a smaller spread compare to 50, the Standard White Bulb; therefore, compare to the one time 750 record, the Soft White Bulb is better.