Answer:
a = 2, r = 5
Step-by-step explanation:
Nth term of a GP = a×r^(n-1)
Where 'a' is the first term and 'r' is the common ratio
4th term = a×r^3 = 250
r^3 = 250/a
7th term = a×r^6 = 31250
a×r^6 = 31250
a×(r^3)^2 = 31250
a×(250/a)^2 = 31250
a×(62500/a^2) = 31250
62500/a = 31250
a = 62500/31250 = 2
a = 2
since r^3 = 250/a,
r^3 = 250/2 = 125
r = (125)^(1/3)
r = 5
parallel
7,14,21,28,35,42,49,56,63,70
18,36,54,72,90,108,126,144,162,180
