power 4dBox4d services offer statistics on 4d and Toto results for Singapore and Malaysia prediction. 4D search,Toto search,4d analysis, winning solution. Box4d Results 4D results ... [Given, Power of convex lens=4D. Placed at 40 cm from a wall. To Find, Distance of a candle. Solution, It is given that ,Power = 4D. Then, P = 1f. So, 4 D = 1f