Jack's manufacture company have experienced inflation for the past three years as follows: the first year's periodic inflation rate is 3%, and the second year's periodic inflation rate is 4%. The average inflation rate for the 3-year period is 5%. What is the periodic inflation rate for the third year?

8.09%

Explanation:

Year          Inflation rate    1 + Inflation rate

1                     0.03                     1.03

2                     0.04                     1.04

3                         x                       1+x

Average rate  0.05                   0.05

1 + Average rate  = [(1+r1)*(1+r2)*(1+r3)]^(1/3)

1.05 = [1.03*1.04*(1*x)]^(1/3)

[1.0712*(1+x)] = (1.05)^3

[1.0712*(1+x)] = 1.157625

1 + x = 1.157625 / 1.0712

1 + x = 1.080681

x = 1.080681 - 1

x = 0.080681

x = 8.09%

Thus, the periodic Inflation rate in year 3 is 8.09%

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