Question

Historically data shows that the diameter of current piston rings is a normally distributed random variable with mean of 12 CM and standard deviation of 0.04 CM

A. If you use 46 randomly select the rings and calculate X bar what is the probability of having an X bar greater than 12.01cm

B. Assume you take 40 rings and put them side-by-side in line what is the probability that the length of the line will exceed 490cm? use original sd

Answer 1

Ans) Given data --- u=12, = 0.04 a) M546 xwall,ao) F awalu, at ". Y = 12 P[*>12.01) = plzs 12.01-12 0.04 V46 = P(2>1.6956 from z-table =o.ouso 6) Here یہ یہ yo nl 40x12, 40x0.04) YN N ( 480 , 1-6) . p(x>490)=plz> 490-480 1-6 =pl Z7 6.25) (from 2-table) =o