Answer:
She has lived
.
Explanation:
Given : Sara has lived 18.0 years.
To find : How many seconds has she lived?
Solution :
Using conversions,
1 year = 365.24 days
1 day = 24 hours
1 hour = 60 minutes
1 minute = 60 seconds
Converting 18 years into seconds,


In scientific notation,

Therefore, she has lived
.