Answer:
8.8 cm
Step-by-step explanation:
-We know that the top 20% of the books are oversized.
-We therefore find the z-value of the top 20%:
[tex]z_{0.1}=8.4[/tex]
#We substitute the z value in formula to solve X.
[tex]z=\frac{\bar X-\mu}{\sigma}[/tex]
Where
- X is the minimum thickness of the book.
-Given [tex]\sigma=0.6 \ , \mu=8.3[/tex], the minimum thickness,X can be calculated as follows:
[tex]z=\frac{\bar X-\mu}{\sigma}\\\\0.84=\frac{\bar X-8.3}{0.6}\\\\\bar X=0.84\times 0.6+8.3\\\\=8.804\approx 8.8\ cm[/tex]
Hence, the minimum thickness of the oversized books is 8.8 cm
