Answer:
A. There is an 84% chance that the shop sells more than 390 CDs in a week.
Step-by-step explanation:
The number of music CDs sold weekly by a store follows a normal distribution with a mean of 455 and a standard deviation of 65.
Hint- First we will have to calculate the z score and then using z score table we can calculate the probability or area below that point.
Z score can be calculated by the following formula,
\(Z=\dfrac{X-\mu}{\sigma}\)
Where,
X = the raw score,
μ = mean of the sample
σ = standard deviation,
Putting the values,
\(Z=\dfrac{390-455}{65}=-1\)
From the z score table, we get
\(P(z<-1)=0.1586=15.86\%\approx 16\%\)
As from the table we get the probability less than the point which in case is 390 with z score of -1, the probability more with z score more than -1, is
\(=100-16=84\%\)
