Answer:
The answer is 20
Step-by-step explanation:
Given that f(2)=1/5
And f(n+1)=f(n)*10
Let's start from n=2
f(2+1)=f(2)*10
f(3)=(1/5)*10
f(3)=2
Now let's take n=3
f(3+1)=f(3)*10
f(4)=2*10
f(4)=20
