A consumer buys 10unit of a commodity at ₹ 5 per unit. He buys 12 units, when price falls to ₹ 4 per units calculate `P.e_(D)` .

Explanation

`{:(P" " 5),(P_(1)" "4),(overlineunderline(DeltaP-1)):}" "{:(Q" "10),(Q_(1)" "12),(overlineunderline(DeltaQ-2)):}`
`(DeltaQ=Q_(1)-Q&DeltaP=DeltaP_(1)-P`
`P.e_(D)= P/Qxx(DeltaQ)/(DetlaP)= 5/10xx2/(-1)`
`P.e_(D)= (-)1`
or `|P.e_(D)|=1` ( unitary elastic demand)