Data Interpretation: University Student Majors

Total Physics majors $= 18 + 36 + 80 + 40 + 23 + 28 = 225$. Since Physics represents $18\%$ of total students, Total Students $= \frac{225}{0.18} = 1250$. Chemistry majors $= 14\% \text{ of } 1250 = 0.14 \times 1250 = 175$.

Proportion of Physics majors from Delhi $= \frac{18}{225} = \frac{2}{25}$. Total Engineering majors $= 20\% \text{ of } 1250 = 250$. Engineering majors from Delhi $= \frac{2}{25} \times 250 = 20$.

Total students from Chennai $= 12\% \text{ of } 1250 = 150$. Physics students from Chennai $= 40$. Remaining Chennai students $= 150 - 40 = 110$. Total Economics students $= 12\% \text{ of } 1250 = 150$. Maximum possible Economics students from Chennai $= 110$. Percentage $= \frac{110}{150} \times 100\% = 73.33\% \approx 73\%$.