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- Nov 4th 2008, 10:00 PM #1

- Joined
- Nov 2008
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- 20

## please help

A lamp has two bulbs, each of a type with an average lifetime of 4 hours. The probability density function for the lifetime of a bulb is .

What is the probability that both of the bulbs will fail within 4 hours?

i took the douple integral of this function with bounds from 0 to 4 and got the answer 1 which isn't right where did i go wrong?

- Nov 4th 2008, 11:06 PM #2

- Nov 5th 2008, 07:28 PM #3