Exams › IBPS PO › Quantitative Aptitude

The average age of $x$ students in a group is 20. When 4 new students, each aged 7.5 years, are admitted, the average decreases by 5. What is the value of $x$?

1. 5
2. 3
3. 7
4. 4

Correct answer: 4

Solution

Initial total age is $20x$. After 4 students of age 7.5 join, the total becomes $20x+30$ and the number of students becomes $x+4$. The new average is 15, so $(20x+30)/(x+4)=15$, which gives $x=4$.

Related IBPS PO Quantitative Aptitude questions

• Find the difference between the average temperature on Saturday and Tuesday together and the average temperature on Wednesday and Saturday together. (i) The average temperature on Saturday, Tuesday and Wednesday is 45 degrees. (ii) The sum of the temperatures on Tuesday and Wednesday is 115 degrees. (iii) The sum of the temperatures on Tuesday and Saturday is 80 degrees.
• The ratio of A to B is 3:4, and the average of A, B and C is 40. If the average of A and B is 35, then find the value of C.
• The average expenditure of Manoj and Nawaz is ₹4500, which is 10% less than that of Sanjay and Irfan. Sanjay spends ₹500 more than Nawaz, and the average expenditure of Nawaz and Sanjay is ₹4250. Find the average expenditure of Manoj and Irfan (in ₹).
• The average age of 20 students in a class is 9 years. If 10 new students are admitted, the average age of the class increases by 6 months. Find the average age of the newly admitted students.
• The average age of 25 students of a class is 16 years. If the age of the class teacher is included, the average increases by 1. Find the age of the class teacher.
• In a classroom consisting of boys and girls, the average marks obtained by the boys is 90. If the average of the whole class is 92, and the ratio of the number of boys to girls is 3:2, what is the average marks scored by the girls?

⚔️ Practice IBPS PO Quantitative Aptitude free + battle 1v1 →