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Help Save & Exit Submi 2, 4, 4S, 5) mine a reasonable free-service period for a

ID: 418401 • Letter: H

Question

Help Save & Exit Submi 2, 4, 4S, 5) mine a reasonable free-service period for a model it will A manufacturer of programmable calculators is attempting to deterr introduce shortly. The manager of product testing has indicated that the calculators have an expected life of 39 months. Assume product life can be described by an exponential distribution. 2.60 2.70 2.80 2.90 3.00 3.10 3.28 3.38 3.48 3.50 3.68 3.70 3.80 3.90 4.00 4.10 4.20 0.8661 .9055 8. 0050 0.0045 0.0041 8.0037 0.0033 8.6030 .9827 9.8825 .8022 0.8020 8.8818 0.8017 0.0015 0.0014 0.0012 5.10 5.20 5.30 0.0743 0.0672 , 0608 .9558 0.0498 8.8450 8.8488 8.8369 0.0334 0.8302 0.8273 0.8247 0.0224 0.8202 0.0183 .0166 0.0150 0.9848 .8187 8.7488 8.6703 0.2 0.30 8.48 0.58 8.60 8.70 8.80 8.90 1.80 .6865 0.5488 8.4966 8.4493 8.4066 0.3679 .3329 0.3012 0.2725 8.2466 8.2231 0.2019 0.1827 5.50 5.68 5.70 5.88 5.98 6.00 6.10 6.20 6.30 6.40 6.58 6.60 6.70 1.2 1.30 1.40 1.50 1.60

Explanation / Answer

1. (a) The items which are expected to fail during service period

Here T/ MTBF = 1.0 that corresponds to exp ( -T/MTBF) = 0.3679

Expected percentage = 100 ( 1-0.3679) = 0.6321 x100 = 63.21%

2. (b) In this case,  exp ( -T/MTBF) = (1-0.2429) = 0.7571

which corresponds to  T/ MTBF = 0.277

Service period = 39 months x0.277 = 10.8 months =11 months