A batch of 30 students took an intelligence test in an institution. 20 of them scored an average of 75 marks and the remaining students scored an average of 87 marks. What is the average score of the entire batch of students?

79

Sum of age of 20 students = 20 × 75 = 1500 years

Sum of age of 10 students = 10× 87 = 870 years 

Average age of whole batch = \(\frac{1500 + 870 }{30}\)

= \(\frac{2370 }{30}\) = 79 years