where r is written as a decimal. What is the formula for the interest rate, r; required to achieve a balance of B in the account after 3 years?

Answer:
Option b
r = -1 + (∛B/10)
Step-by-step explanation:
Given in the question that formula to calculate future amount B, after 3 years if principal amount 1000 is deposit with interest rate r is
B = 1000(1+r)^3
B/1000 = (1+r)^3
∛(B/1000) = 1 + r
∛B/∛1000 = 1 + r
∛B/10 = 1 + r
(∛B/10) - 1 = r
r = -1 + (∛B/10)