Answer :
Given information :
The population mean $(μ) = 9$
The population standard deviation $(σ) = 0.9$
Solution :
→ The probability that an item will take between 7.5 and 7.9 hours to move through the assembly line :
$$\therefore P(7.5 < x < 7.9) = P\left(\frac{7.5 – 9}{0.9} < \frac{x – \mu}{\sigma} < \frac{7.9 – 9}{0.9}\right)$$ $$= P(-1.67 < z < -1.22)$$ $$= P(z < -1.22) – P(z < -1.67)$$ $$= 0.111 – 0.047$$ $$= 0.064$$
