Target overall average across three equal-maximum exams: Out of three annual exams (each out of 600), Lalit scored 55% in the first and 60% in the second. How many marks must he score in the third to make his overall average 70%?

Introduction / Context:
This involves translating percentages to marks, then working backward from a target overall percentage across equal-maximum papers.

Given Data / Assumptions:

• Each exam max = 600
• First = 55% of 600, Second = 60% of 600
• Target overall average = 70% of 600

Concept / Approach:
Compute current total, compute required total for three papers, subtract to get the third paper requirement.

Step-by-Step Solution:
First = 0.55 * 600 = 330Second = 0.60 * 600 = 360Required total for overall 70% = 3 * (0.70 * 600) = 3 * 420 = 1260Third needed = 1260 - (330 + 360) = 1260 - 690 = 570

Verification / Alternative check:
Totals become 330 + 360 + 570 = 1260. Average per exam = 1260 / 3 = 420, i.e., 70%.

Why Other Options Are Wrong:
560, 590, 500, 540 do not yield an overall 70% when summed with the first two scores.

Common Pitfalls:
Taking 70% of the current average rather than recalculating totals across all three equal-weight components.

Final Answer:
570