For this case we have a function of the form:
y = A * (b) ^ t
Where,
A: initial amount
b: growth rate
t: time
For each of the questions we must make use of this equation in the following way:
Part A:
y = 6.81 * (1.0161) ^ t
Part B:
y = 6.81 * (1.0161) ^ 6
y = 7.49 million
Part C:
10 = 6.81 * (1.0161) ^ t
log1.0161 ((1.0161) ^ t) = log1.0161 ((10 / 6.81))
t = log1.0161 ((10 / 6.81))
t = 24.05 years
Part D:
2 * 6.81 = 6.81 * (1.0161) ^ t
log1.0161 ((1.0161) ^ t) = log1.0161 ((2 * 6.81 / 6.81))
t = log1.0161 (2)
t = 43.40 years