Question

Consider two different types of motors. Motor A has a characteristic life of 4100 hours (based on a MTTF of 4650 hours) and a shape parameter B = 0.8. Motor B has a characteristic life of 336 hours (based on a MTTF of 300 hours) with a shape parameter B = 3.0. Which of these offers better reliability for 100 hours? Which of these offers better reliability for 750 hours?

Answer 1

Answer:B

Step-by-step 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

`R_a=e^{-\left ( (T-r)/(n)\right )B}`

`R_a=e^{-\left ( (4650-4100)/(100)\right )0.8}`

`R_a=e^(-4.4)=0.01227`

For B

`R_b=e^{-\left ( (300-336)/(100)\right )3}`

`R_b=e^(1.08)=2.944`

B is better for 100 hours

(b)For 750 hours

`R_a=e^(-0.5866)=0.55621`

`R_b=e^(0.144)=1.154`

So here B is more Reliable.