6.61 Wires manufactured for use in a certain computer system are specified to have resistances between 0.12 and 0.14 ohm. The actual mea-

P(-z0 … Z … z0) = 0.95 P(-z0 … Z … z0) = 0.90 P(Z Ú z0) = 0.617 P(Z Ú z0) = 0.117 P(Z … z0) = 0.8749 P(Z … z0) = 0.5 z0 P(-200 … Z … -1.56)

P(-0.2 … Z … 0.2)

P(0.3 … Z … 1.56)

P(-0.9 … Z … 0)

P(0 … Z … 1.2)

sured resistances of the wires produced by Company A have a normal probability distribution with a mean of 0.13 ohm and a standard deviation of 0.005 ohm.

a What is the probability that a randomly selected wire from Company A’s production will meet the specifications?

b If four such wires are used in the system and all are selected from Company A, what is the probability that all four will meet the specifications?