Question

a certain machine makes electrical resistors having a mean resistance of 40 ohms and standard deviation of 2 ohms what is the probability that random sample of 36 have combined resistance more than 1458

Answer 1

$$1458/36=40.5$$

$$P(X>40.5)=1-P(Z\le\dfrac{40.5-40}{2/\sqrt{36}})$$

$$=1-P(Z\le1.5)\approx0.0668$$