The probability that an oven will have failed after 1000 hours of use is 0.09 . What is the probability that it will still be working after 1000 hours of use? Give your answer as a decimal.

Step 1 ：The probability that an oven will have failed after 1000 hours of use is 0.09.

Step 2 ：The probability of an event happening and the probability of the same event not happening are complementary. This means that they add up to 1.

Step 3 ：So, to find the probability that the oven will still be working after 1000 hours of use, we subtract the probability that it will have failed from 1.

Step 4 ：\(probability_{failed} = 0.09\)

Step 5 ：\(probability_{working} = 1 - probability_{failed} = 1 - 0.09 = 0.91\)

Step 6 ：Final Answer: The probability that the oven will still be working after 1000 hours of use is \(\boxed{0.91}\).