Example 11 - Chapter 1 Class 8 - Fractions in Disguise (Ganita Prakash II)

Transcript

Example 11 The population of a village was observed to be reducing by about 10% every decade. If the current population is 1250, what is the expected population after 3 decades?Since population is decreasing every decade by 10% So, we Put a Minus sign in rate Rate = −10% Now, Given Current Population = Principal = P = 1,250 Rate of depreciation = R = –10% = (−10)/100=(−𝟏)/𝟏𝟎 Since Rate is per decade, time is calculated in decades Thus, T = Number of decades = 3 We need to find expected population after 3 decades, Thus, we need to find A We use the formula A = P (𝟏+𝑹)^𝒕 Putting Values in Formula A = 1,250(1+((−1)/10))^3 A = 𝟏,𝟐𝟓𝟎(𝟏−𝟏/𝟏𝟎)^𝟑 A = 1,250((10 − 1)/10)^3 A = 𝟏,𝟐𝟓𝟎(𝟗/𝟏𝟎)^𝟑 A = 1,250 ×729/1000 A = 91125/100 A = 911.25 Rounding off, we can say that the expected population after 3 decades will be around 911