Formula for Combined Mean ($\bar{x}_{12}$):
$$\bar{x}_{12} = \frac{n_1 \bar{x}_1 + n_2 \bar{x}_2}{n_1 + n_2}$$Given:
$n_1 = 50, \bar{x}_1 = 53.7$
$n_2 = 100, \bar{x}_2 = 52.3$
Calculation:
$$n_1 \bar{x}_1 = 50 \times 53.7 = 2685$$ $$n_2 \bar{x}_2 = 100 \times 52.3 = 5230$$ $$\bar{x}_{12} = \frac{2685 + 5230}{50 + 100} = \frac{7915}{150} = 52.7667... \approx 52.767$$- Note on NTA Key: The exact mathematical value is 52.767. NTA printed Option 2 as '52.786' due to a typographical digit transposition in the question paper, and officially keyed Option 2.
संयुक्त माध्य का सूत्र: $\bar{x}_{12} = \frac{n_1 \bar{x}_1 + n_2 \bar{x}_2}{n_1 + n_2}$।
गणना: $\frac{50 \times 53.7 + 100 \times 52.3}{150} = \frac{7915}{150} = 52.767$। प्रश्न पत्र में मुद्रण त्रुटि (अंकों के उलटफेर) के कारण विकल्प 2 में '52.786' लिखा गया था, जिसे NTA ने सही माना है।