If the mean of 50 students is 40 and that of other 100 students is 50, then the combined mean of group of 150 is

Sum of 50 students  $=50\times 40=2000$

Mean of 100 students $=50$

Sum of 100students $=100\times 50=5000$

Combined mean $=\frac{\text{sum of 50 students }+\text{sum of 100 students }}{100+50}$

$=\frac{2000+5000}{150}=\frac{7000}{150}=46.66$