Answer:
About 3 years Speedy Jet printers be guaranteed.
Step-by-step explanation:
Given : Quality control studies for Speedy Jet Computer Printers show the lifetime of the printer follows a normal distribution with
mean
and standard deviation 
If the company wishes to replace no more than 10% of the printers.
To find : How long should Speedy Jet printers be guaranteed ?
Solution :
Using Z- table,
Z value corresponding to 10% or 0.10 = -1.28.
Applying z-score formula,

The value of x is given by,

Substitute the values,



So, approx 3 years.
Therefore, About 3 years Speedy Jet printers be guaranteed.
I think it would be c if it were a greater rate I don't know if i am right I'll check back with you guys on the answer
Answer:
11 weeks
Step-by-step explanation:
5÷1/2=10
10+1=11
Sorry if I'm wrong