Rs 3600 is divided into two parts such that one part is put out at 3% and the other at 5%. If the annual interest earned from both the investments be Rs 144, find the first part. Pick
A) s 4000 B) s 2800 C) s 1800 D) s 3500 E) s 3100

Rationale: "explanation : average rate = ( 144 / 3600 ) * 100 = 4 ratio = 1 : 1 so , first part = ( 1 / 2 ) * 3600 = rs 1800 . answer : c"
Answer: C