Solution -
Given,
P = 400
A = 441
R = r%
T = 2
A = P (1 + (r/100))n
441 = 400 (1 + (r/100))2
441 / 400 = (1 + (r/100))2
(441 / 400)½ = 1 + (r/100)
21 / 20 = (100 + r) / 100
2100 / 20 = 100 + r
105 = 100 + r
105 - 100 = r
r = 5
Therefore,
The value of 'r' is 5%
Hence,
The correct answer is option (b) 5%.
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