Wax-Com Electronics Inc $$Z = \frac { 8.5 - 25 ( .5 ) } { \sqrt { ( .5 ) ( 1 - .5 ) ( 25 } } = \frac { - 4 } { 2.5 } = - 1.6$$

Multiple Choice

Wax-com Electronics Inc.claims that a certain circuit board has a median operating life of less than 20,000 hours.A random sample of 25 such circuit boards showed 8 circuit boards failing before 20,000 hours and 17 circuit boards failing after 20,000 hours.Assume the useful life of the circuit board is not normally distributed.At ? = .05,can it be concluded that the sample contradicts the company's claim? Assume the useful life of the circuit board is not normally distributed.

A) Reject the null hypothesis.
B) Do not reject the null hypothesis.
$$Z = \frac { 8.5 - 25 ( .5 ) } { \sqrt { ( .5 ) ( 1 - .5 ) ( 25 } } = \frac { - 4 } { 2.5 } = - 1.6$$