
Answer:
n this question, we are asked to find the probability that Â
R1 is normally distributed with mean 65 Â and standard deviation 10
R2 is normally distributed with mean 75 Â and standard deviation 5
Both resistor are connected in series.
We need to find P(R2>R1)
the we can re write as,
P(R2>R1) = P(R2-R1>R1-R1)
P(R2>R1) = P(R2-R1>0)
P(R2>R1) = P(R>0)
Where;
R = R2 - R1
Since both and are independent random variable and normally distributed, we can do the linear combinations of mean and standard deviations.
u = u2-u1
u = 75 - 65 = 10ohm
sd = √sd1² + sd2²
sd = √10²+5²
sd = √100+25 = 11.18ohm
Now we will calculate the z-score, to find  P( R>0 )
Z = ( X -u)/sd
the z score of 0 is
z = 0 - 10/11.18
z= - 0.89