Answer:B
Explanation:
Given
For motor A
Characteristic life(r)=4100 hr
MTTF=4650 hrs
shape factor(B )=0.8
For motor B
Characteristic life(r)=336 hr
MTTF=300 hr
Shape Factor (B)=3
Reliability for 100 hours
[tex]R_a=e^{-\left ( \frac{T-r}{n}\right )B}[/tex]
[tex]R_a=e^{-\left ( \frac{4650-4100}{100}\right )0.8}[/tex]
[tex]R_a=e^{-4.4}=0.01227[/tex]
For B
[tex]R_b=e^{-\left ( \frac{300-336}{100}\right )3}[/tex]
[tex]R_b=e^{1.08}=2.944[/tex]
B is better for 100 hours
(b)For 750 hours
[tex]R_a=e^{-0.5866}=0.55621[/tex]
[tex]R_b=e^{0.144}=1.154[/tex]
So here B is more Reliable.
