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Worked Examples · Example 1
Q.

Suppose we want to compare price level of crude oil for the years 2005 through 2020.

PeriodPrice (thousand ₹ / gallon)
December 20052.5
January 20103.5
November 20152.8
October 20202.9

(Source courtesy: https://www.indexmundi.com/commodities/?commodity=crudeoil&months=180&currency=inr)

Yanam CbseNCERTSubjective· 3mImportance★★★★★est
3% · 1/40 Questions
✓ Free question

Using December 2005 (₹2.5) as the base, each period's price relative =ptp0×100=\frac{p_t}{p_0}\times100 gives 100, 140, 112 and 116 — prices peaked in 2010 (40% above base) and settled 16% above base by 2020.

Price relative =ptp0×100=\dfrac{p_t}{p_0}\times100, where ptp_t = price in the given period, p0p_0 = base-period price (December 2005 == ₹2.5 thousand/gallon).

  1. Base value. p0=p_0= ₹2.5 (Dec 2005), which is set to index 100.
  2. Compute each price relative.
PeriodPrice ptp_t (₹ thousand/gal)Price relative =pt2.5×100=\frac{p_t}{2.5}\times100
December 20052.52.52.5×100=100.0\frac{2.5}{2.5}\times100=100.0
January 20103.53.52.5×100=140.0\frac{3.5}{2.5}\times100=140.0
November 20152.82.82.5×100=112.0\frac{2.8}{2.5}\times100=112.0
October 20202.92.92.5×100=116.0\frac{2.9}{2.5}\times100=116.0
  1. Interpret. Relative to Dec 2005, crude-oil prices were 40% higher in Jan 2010, 12% higher in Nov 2015, and 16% higher in Oct 2020.
✓Final answer

Price index numbers (base Dec 2005 =100=100): Dec 2005 = 100, Jan 2010 = 140, Nov 2015 = 112, Oct 2020 = 116.

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