Answer:
15 years.
Step-by-step explanation:
We have the equation:
20000 = 10000(1 + 0.048)^t where t is the number of years.
1.048 t = 20000/10000 = 2
Taking logs:
t ln 1.048 = ln 2
t = ln 2 / ln 1.048
t = 14.78
Each runners time would be an average of 18.1
72.4/4=18.1
48
+14
-------
62
If you need more work:
Ones place: 8+4=12
Tens place: 40+10=50
Add up: 50+12=62
