What is the expected time for the first of these bulbs to burn out?

Apr 2017
45
0
PA
A company buys 100 lightbulbs, each of which has an exponential lifetime of
1000 hours. What is the expected time for the first of these bulbs to burn
out?
For this, I divided 1000/100 to get 10 hours, is this correct?
 

romsek

Math Team
Sep 2015
2,762
1,540
USA
Can you explain why you did this.

I believe it is the correct answer but a fair bit of work was needed to show this.

Were you given some formula?