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.
15x = 292.50
Divide 15 from both sides
X= 5.85
1 T-shirt = $5.85
45x = 747.50
Divide 45 from both sides
X= 16.61
1 T-shirt = $ 16.61
This one is similar to the previous one.
Answer:

Step-by-step explanation:

You can confirm this by working and expanding backwards:

Hope this helps!