Average Worksheet-4

Average Worksheet-4

1. The average of 8 numbers is 20. The average of first two numbers is and that of the next three is . If the sixth number be less than the seventh and eighth numbers by 4 and 7 respectively, then the eighth number is:

(a) 18                  (b) 22                 (c) 25                  (d) 27

2. If the arithmetic mean of seventy–five numbers is calculated, it is 35. If each number is increased by 5, then mean of new numbers is:

(a) 30                 (b) 40                 (c) 70                  (d) 90

3. The average of ten numbers is 7. If each number is multiplied by 12, then the average of the new set of numbers is:

(a) 7                    (b) 19                  (c) 82                  (d) 84

4. Average of ten positive numbers is . If each number is increased by 10%, then :

(a) remains unchanged               (b) may decrease

(c) may increase                           (d) is increased by 10%

5. The mean of 50 observations was 36. It was found later that an observation 48 was wrongly taken as 23. The corrected new mean is:

(a) 35.2              (b) 36.1              (c) 36.5              (d) 39.1

6. A pupil's marks were wrongly entered as 83 instead of 63. Due to that the average marks for the class got increased by half. The number of pupils in the class is:

(a) 10                  (b) 20                 (c) 40                  (d) 73

7. The average age of 15 students of a class is 15 years. Out of these, the average age of 5 students is 14 years and that of the other 9 students is 16 years. The age of the 15th student is:

(a) 11 years        (b) 14 years       (c) 15 years        (d) years

8. The average of 11 numbers is 10.9. If the average of the first six numbers is 10.5 and that of the last six numbers is 11.4, then the middle number is:

(a) 11                   (b) 11.3               (c) 11.4               (d) 11.5

9. The average weight of three boys A, B and C is kg, while the average weight of three boys B, D and E is 53 kg. What is the average weight of A, B, C_; D and E?

(a) 52.4 kg         (b) 53.2 kg         (c) 53.8 kg         (d) Data inadequate

(e) None of these

10. The average temperature of the town in the first four days of a month was 58 degrees. The average for the second, third, fourth and fifth days was 60 degrees.  If the temperatures of the first and fifth days were in the ratio 7 : 8, then what is the temperature on the fifth day?

(a) 64 degrees                               (b) 62 degrees

(c) 56 degrees                                (d) None of these

11. The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is Rs. 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is:

(a) Rs. 3500      (b) Rs. 4000     (c) Rs. 4050      (d) Rs. 5000

12. The average age of 36 students in a group is 14 years. When teacher's age is included to it, the average increases by one. What is the teacher's age in years?

(a) 31                                               (b) 36

(c) 51                                               (d) Cannot be determined

(e) None of these

13. The average monthly salary of 20 employees in an organisation is Rs. 1500. If the manager's salary is added, then the average salary increases by Rs. 100. What is the manager's monthly salary?

(a) Rs. 2000     (b) Rs. 2400     (c) Rs. 3600      (d) Rs. 4800

14. The average weight of a class of 24 students is 35 kg. If the weight of the teacher be included, the average rises by 400 g. The weight of the teacher is:

(a) 45 kg            (b) 50 kg            (c) 53 kg             (d) 55 kg

15. The average age of the mother and her six children is 12 years which is reduced by 5 years if the age of the mother is excluded. How old is the mother?

(a) 40 years       (b) 42 years       (c) 48 years       (d) 50 years

Answer Key:

(1)-c; (2)-b; (3)-d; (4)-d; (5)-c; (6)-c; (7)-a; (8)-d; (9)-d; (10)-a; (11)-b; (12)-c; (13)-c; (14)-a; (15)-b