If l, m,n are in ap and p, q,r in gp, prove that
p^m-n. q^n-l. r^l-m

Which of the following would be a reasonable estimate for the weight of a pencil? a. 1 × 10^-20 lb b. 1 × 10^20 lb c. 1 × 10^2 lb d. 1 × 10^-2 lb