If a distance of 50 m is covered in 1 minute, 90 m in 2 minutes and 130 m 3 minutes. Find the distance covered in 15th minute.

Answer: Option A

Distance covered in 1 min = 50 m
Distance covered in 2 min = 90 m
Similarly, 1^st min, 2^nd min, 3^rd min . . . . . 15^th
Distance → 50 m + 90 m + 130 m + . . . . . . . .
By using A.P.
a = 50 m
d = (90 - 50) = 40 m
Tn = a + (n - 1)d
     = 50 + (15 - 1) × 40
     = 50 + 560
     = 610 minutes