Answer:
time = 28 years
Explanation:
Given,
principal amount = $10,000
rate = 4%
total amount = $30,000
According to compound interest formula

where, A = total amount
P = principal amount
r = rate
t = time in years
so, from the question we can write,



by taking log on both sides, we will get
=> log3 = t.log(1.04)

=> t = 28.01
So, the time taken to get the amount from 10000 to 30000 is 28 years.