Number series – next term with decreasing differences by 15: 325, 314, 288, 247, 191, ?

Introduction / Context:
Here the series decreases, but not by a constant. The first differences themselves fall by a fixed amount, a common pattern in aptitude tests.

Given Data / Assumptions:

• Differences: 314−325=−11, 288−314=−26, 247−288=−41, 191−247=−56.

Concept / Approach:
Each difference drops by 15: −11, −26, −41, −56 → next is −71. Apply this to the last term.

Step-by-Step Solution:

Verification / Alternative check:
Back-check: 120−191 = −71, consistent with the −15 step-down in differences.

Why Other Options Are Wrong:

Common Pitfalls:
Assuming a constant decrement; instead, the decrement itself decreases linearly.

Final Answer:
120