The consumer price index for June, 2005 was 125. The food index was 120 and that of other items. What is the percentage of the total weight given to food?
Item IndexWeightsWIFood120(W1)120(W1)Other Items135(W2)135(W2)∑W=100∑WI=120W1+135W2
Let the total weight = 100
W1 denotes weight of food
W2denotes weight of other items
So, W1+W2=100.... Eqn (i)
CPI = 125
CPI = ∑WR∑W
125 = 120W1+135W2100
12500 = 120W1+135W2.... Eqn (ii)
Multiplying both sides of Eq. (i) by 135 and subtracting Eq. (ii) From (i) we get
13500 = 135W1+135W2
12500 = 120W1+135W2
13500 = 135W1+135W2
(−)(−)(−)1000=15W1+0
So, W1=100015=66.67
Substituting the value of W1 in the Eq. (i) , we get
W1+W2=100
or 66.67+W2=100
W2=33.33
Therefore, percentage of total weight given to food is 66.67% and other items 33.33%