RRB Assistant Loco Pilot and Technician Model Paper 8 with solutions

nth term of A.P. is given by
${\mathit{a}}_{\mathit{n}}$= a + (n –1) d where,
a is first term and d is comm. diff.
${\mathit{a}}_4$= a + (4 – 1) d
${\mathit{a}}_4$= a + 3d
from question,
4(a + 3d) = 7a
or 4a + 12d = 7a
or 3a = 12d
a = 4d
∴ ratio of first term to comm. diff
$\frac{\mathit{a}}{\mathit{d}}=\frac{4\mathit{d}}{\mathit{d}}$ = 4 : 1