Answer:
2.94% is the percentage of the company’s callers put on hold for at least 4.8 minutes
Step-by-step explanation:
First of all, what we need to find here is the z-score
Mathematically;
z-score = x-mean/SD
where mean = 3.1 , SD = 0.9 and x = 4.8
Plugging these values we have;
Z-score = (4.8-3.1)/0.9 = 1.89
So the required probability we want to calculate is;
P(z > 1.89) = 0.0294
So the proportion of callers put on hold for at least 4.8 minutes is 2.94%