Answer:
The proportion of these light bulbs that will last less than the advertised time is 18.94% or 0.1894
Step-by-step explanation:
The first thing to do here is to calculate the z-score
Mathematically;
z-score = (x - mean)/SD
= (1500-1550)/57 = -50/57 = -0.88
So the proportion we will need to find is;
P( z < -0.88)
We shall use the standard score table for this and our answer from the table is 0.1894 which is same as 18.94%
