Question

If the public debt of a country in 2009 was $12,752,000,000 in the budget for 2010 was in deflicit by $201,645,000,000, what was the public debt in 2007

Answer 1

Y = $12,752,000,000,000 + $201,645,000,000 = 12,953,645,000,000
x = $12,752,000,000,000
r = ?n = 2010 - 2009y = x(r + 1)ⁿ
12,953,645,000,000 = 12,752,000,000,000 * (r + 1)¹
12,953,645,000,000 ÷  12,752,000,000,000 = (r + 1)¹
1.016 = r + 1
r = 1.016 - 1
r = 0.016
y = $12,752,000,000,000    (since it is in 2009, this is future value)
x = ?   (initial value in 2007
r = 0.016
n = 2009 - 2007 = 2


y = x(r + 1)ⁿ
12,752,000,000,000 = x(0.016 + 1)²
12,752,000,000,000 = x(1.016)²
12,752,000,000,000 = x * 1.032
x = 12,752,000,000,000 ÷ 1.032
x = 12,356,589,147,287 the answer