AVERAGE (CDS)

Total Questions: 23

11. The average of the ages of 15 students in a class is 19 yr. When 5 new students are admitted to the class, the average age of the class becomes 18.5 yr. What is the average age of the 5 newly admitted students? [2018 (I) Morning Shift ]

Correct Answer: (a) 17 year
Solution:Average age of 15 students =19 year

12. A small company pays each of its 5 category ‘C’ workers ₹20,000, each of its 3 category ‘B’ workers ₹25,000 and a category ‘A’ worker ₹65,000. The number of workers earning less than the mean salary is [2017 (II) Evening Shift ]

Correct Answer: (a) 8
Solution:

13. The average height of 22 students of a class is 140 cm and the average height of 28 students of another class is 152 cm. What is the average height of students of both the classes? [2017 (II) Evening Shift ]

Correct Answer: (c) 146.72 cm
Solution:

14. Let a, b, c, d, e, f, g be consecutive even numbers and j, k, l, m, n be consecutive odd numbers. What is the average of all the numbers ? [2017 (I) Morning Shift ]

Correct Answer: (d)
Solution:Let a = x (even)

15. An individual purchases three qualities of pencils. The relevant data is given below [2017 (I) Morning Shift ]

It is known, the average price per pencil is ₹1.25. What is the value of x?

Correct Answer: (b) ₹30
Solution:

16. The average score of class X is 83. The average score of class Y is 76. The average score of class Z is 85. The average score of class X and Y is 79 and average score of class Y and Z is 81. What is the average score of X, Y and Z? [2016 (II) Evening Shift ]

Correct Answer: (a) 81.5
Solution:We have,


17. A cricketer has a certain average of 10 innings. In the eleventh inning he scored 108 runs, there by increasing his average by 6 runs. What is his new average? [2016 (II) Evening Shift ]

Correct Answer: (c) 48
Solution:Let the average run of cricketer in 10 innings be x.

18. The average of m numbers is n⁴ and the average of n numbers is m⁴ . The average of (m + n) numbers is [2015 (II) Evening Shift ]

Correct Answer: (d) mn (m² + n² - mn)
Solution:

19. The average weight of students in a class is 43 kg. Four new students are admitted to the class whose weights are 42 kg, 36.5 kg, 39 kg and 42.5 kg, respectively. [2015 (II) Evening Shift ]

Now, the average weight of the students of the class is 42.5 kg. The number of students in the beginning was

Correct Answer: (c) 20
Solution:Let the number of students be n.

20. 4 year ago, the average age of A and B was 18 year. Now, the average age of A, B and C is 24 year. After 8 year, the age of C [2015 (II) Evening Shift ]

Correct Answer: (c) 36 year
Solution:Let present ages of A B, andC be x y, and z, respectively.