Hypothesis Testing We are estimating the spares requirement for a radar power supply. The power supply was designed with a mean (μ) life of 6500 hours. The standard deviation (σ) determined from testing is 750 hours. What is the likelihood that a power supply would fail between 4500 and 7670 hours? .4406 or 44.06% .0556 or 5.56% .4962 or 49.62% .9368 or 93.68%