.0150

6.70 .0012

1.80 .1653

4.30 .0136

6.80 .0011

1.90 .1496

4.40 .0123

6.90 .0010

2.00 .1353

4.50 .0111

7.00 .0009

2.10 .1255

4.60 .0101

2.20 .1108

4.70 .0091

2.30 .1003

4.80 .0082

2.40 .0907

4.90 .0074

2.50 .0821

5.00 .0067

**a.**

The probability that any given unit will operate for at least (1) 43 months, (2) 54 months, (3) 60 months. **(Use the "Probability" values to 1 decimal place for intermediate**

**calculations.)**

*T e_{-} T /MTBF*

(1) 43

(2) 54

(3) 60

**b.**

The probability that any given unit will fail sooner than (1) 33 months, (2) 16 months, (3) 5 months. **(Use the "Probability" values to 1 decimal place and other values to 4**

**decimal places for intermediate calculations.)**

*T e_{-} T /MTBF*

(1) 33

(2) 16

(3) 5

**c.**

The length of service time after which the percentage of failed units will approximately equal (1) 55 percent, (2) 85 percent, (3) 90 percent, (4) 98 percent. **(Use the**

**"Probability" values to 1 decimal place and other values to 4 decimal places for intermediate calculations. Round your final answers to the nearest whole number)**

1− *e*_{-} *T* /MTBF^{T} (whole months)

(1) 55%

(2) 85%

(3) 90%

(4) 98%

Problem 4S-18

A major television manufacturer has determined that its 19-inch color TV picture tubes have a mean service life that can be modeled by a normal distribution with a mean of 8 years and a standard deviation of 1.5. What service period would achieve an expected wear-out rate of

Use Table A and Table B .

**a.**

3 percent? **(Round your answer to 2 decimal places.)**

Service period

yr

**b.**

5 percent? **(Round your answer to 2 decimal places.)**

Service period

yr

Problem 4S-15

Planetary Communications, Inc., intends to launch a satellite that will enhance reception of television programs in Alaska. According to its designers, the satellite will have an expected life of four years. Assume the exponential distribution applies.

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- Fall '08
- Olander
- Finance, Probability, Corporate Finance, Economic Development, Decimal, decimal places, Failure rate