1. A student was asked to find the
arithmetic mean of the following
12 numbers :
3, 11, 7, 9, 15, 13, 8, 19, 17,
21, 14 and x
He found the mean to be 12. The
value of x will be :
(1) 3 (2) 7
(3) 17 (4) 31
(SSC CGL Prelim Exam. 04.07.1999
(First Sitting)

2. The average of the marks obtained
in an examination by 8 students
was 51 and by 9 other students
was 68. The average marks of all
17 students was :
(1) 59 (2) 59.5
(3) 60 (4) 60.5
(SSC CGL Prelim Exam. 04.07.1999
(First Sitting)

3. If the average marks of three
batches of 55, 60 and 45 students
respectively is 50, 55 and
60, then the average marks of all
the students is
(1) 54.68 (2) 53.33
(3) 55 (4) None of these
(SSC CPO S.I. Exam. 12.01.2003

4. The average of 30 results is 20
and the average of other 20 results
is 30. What is the average
of all the results ?
(1) 24 (2) 48
(3) 25 (4) 50
(SSC CGL Prelim Exam. 11.05.2003
(First Sitting)

5. If the average weight of 6 students
is 50 kg; that of 2 students
is 51 kg; and that of other 2 students
is 55 kg; then the average
weight of all students is
(1) 61 kg (2) 51.5 kg
(3) 52 kg (4) 51.2 kg
(SSC CGL Prelim Exam. 04.02.2007
(Second Sitting)

6. The average of 10 numbers is 7.
If each number is multiplied by
12, then the average of the new
set of numbers will be
(1) 7 (2) 19
(3) 82 (4) 84
(SSC CGL Prelim Exam. 04.02.2007
(Second Sitting)

7. The average income of 40 persons
is 4200 and that of another
35 persons is 4000. The
average income of the whole
group is :
(1) 4100 (2) 4106 1/3
(3) 4106 2/3 (4) 4108 1/3
(SSC CGL Prelim Exam. 04.07.1999
(Second Sitting)

8. The average weight of five persons
sitting in a boat is 38 kg.
The average weight of the boat
and the persons sitting in the
boat is 52kg. What is the weight
of the boat ?
(1) 228 kg (2) 122 kg
(3) 232 kg (4) 242 kg
Exam.05.02.2012 (Paper-I)
East Zone (IInd Sitting)

9. The average marks of 32 boys of
section A of class X is 60 whereas
the average marks of 40 boys of
section B of class X is 33. The
average marks for both the sections
combined together is
(1) 44 (2) 45
(3) 46 1/2
(4) 45 1/2
(SSC Data Entry Operator
Exam. 02.08.2009)

10- Total weekly emoluments of the
workers of a factory is 1534.
Average weekly emolument of a
worker is 118. The number of
workers in the factory is :
(1) 16 (2)14
(3) 13 (4)12
(SSC CHSL DEO & LDC
Exam. 27.11.2010)

Solution :-    