Question

(b) The price of a commodity increased by 10% in the first year
and by 20% in the second year. However, it decreased by 40% in the
third year. But it again started rising and increased by 5% in the fourth
year. Find the average increase or decrease in the price of the
commodity over the period of four years.
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Answer 1

$\mathfrak{The\:Answer\:is}$

Let r% be the average increase or decrease in the price

then,

(1+r/100)^4 = (1+10/100)(1+20/100)(1-40/100)(1+5/100)

=> (1+r/100)^4 = 1.1*1.2*0.6*1.05

=>(1+r/100) = (0.8316)^1/4

=>r/100 = 0.955-1

=>r = - 4.5%

Hence there is an average decrease of 4.5% in the price of the

commodity over the period of four years.

$\boxed{Hope\:This\:Helps}$