Answer:
=0.1587 or 15.87%
So option A is correct answer so 15.87% of the invoices were paid within 15 days of receipt.
Step-by-step explanation:
In order to find the percent of the invoices paid within 5 days of receipt we have to find the value of Z first.
where:
X is the random varable which in our case is 15 days
u is the mean or average value which is 20 days
S is the standard deviation which is 5 days
Z=-1.0
We have to find Probability at Z less than -1
P(Z<-1.0) which can be written as:
=1-P(Z>1.0)
From Cumulative distribution table:
=1-(0.3413+0.5)
=0.1587 or 15.87%
So option A is correct answer so 15.87% of the invoices were paid within 15 days of receipt.