Answer:
This is a compound interest formula, where P = principal, r = rate, n = # compoundings per yr, t = time (in years).
P = 3000
r = 7% = 0.07
t = 6
n = 2 (semi-annually)
a) A = 3000(1 + 0.07/2)^(2*6) = $4,533.21
b) A = 3000(1 + 0.07/12)^(12*6) = $4,560.32
Continuous compounding: A = Pe^(rt)
c) A = 3000(2.7183)^(0.07*6) = $4,565.90
Explanation: