3. The price of an article which was 150 in 2005 increased to 300 in 2007. The increase in 2007 On the base year 2005 was 100%. So using 2007 as base year the decrease in 2005 should have been: (Choose the correct alternative). a. 150% b. 100% c. 200% d. 50%

Dear Student,
Your question seems to be unclear as it seems that you have not posted the complete query. On the basis of available information and suitable assumptions, the question has been solved hereunder:- 

Prices in 2005 (P1)	Prices in Base year, 2007 (Po)
150	300

Index Number =  Total of (P1) / Sum Total of (Po) x 100
 = 150 / 300 x 100
= 50

Henceforth, Option D is correct.
Kindly post the complete question. So that we can provide you the solution of the same.

Regards