A manufacturer's quality conrol department is testing the number of steel beams that conform to national safety regulatons. Suppose that 1000 beams are tested, and each beam has a 0.1% chance of not conforming to regulations. Let the random variable X denote the number of steel beams that do not pass the safety test.
Suppose now that the equipment used to test the steal beams is faulty, and each beam has a 50% chance of failing the test. X can be approximated by which of the following(only answer one choice):
a) Poisson(500)
b) Binomial(1000,0.001)
C) Normal(1000,0.5)
D) Normal(500,250)