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Unformatted text preview: UF-ESI-6321 UF-ESI-6321-04-04.xmcd page 1 of 2 4.4 A company manufacturing stereo equipment claims that their personal CD player can be used for approximately t := 8 hr of continuous play when used with alkaline batteries. To provide this estimate, the company tested n := 35 CD players with new alkaline batteries and recorded the time at which the batteries in the players "lost power." The average time was Xbar := 8.3 hr with a sample standard deviation of S := 1.2 hr (a) Construct a 95% confidence interval for the mean time until a new alkaline battery used in the CD player loses power. The value of n exceeds 30 which makes this analysis valid. Z95 := 1.960
upper := Xbar + Z95 = 8.7 hr := Xbar - Z95 = 7.9 hr S n upper S n lower lower Luther Setzer 1 NASA Pkwy E Stop NEM3, Kennedy Space Center, FL 32899 (321) 544-7435 UF-ESI-6321 UF-ESI-6321-04-04.xmcd page 2 of 2 (b) Determine the required sample size in order to estimate the mean time until a new alkaline battery used in the CD player loses power to within 10 minutes at the 99%confidence level. t := 10 min t = 0.167 hr
Z99 := 2.576
upper := Xbar + t = Xbar + Z99 S n S n upper Xbar + t = Xbar + Z99 t = Z99 S n n := ceil Z99 t S
2 n = 344 The value of n exceeds 30 which makes this analysis valid. Luther Setzer 1 NASA Pkwy E Stop NEM3, Kennedy Space Center, FL 32899 (321) 544-7435 ...
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This note was uploaded on 05/12/2010 for the course ESI 6321 taught by Professor Josephgeunes during the Spring '07 term at University of Florida.
- Spring '07