Question

Consider the frequency distribution of the given numbers

Value :	1	2	3	4
Frequency :	5	4	6	f

If the mean is known to be 3, then the value of f is

• A. 3
• B. 7
• C. 10
• D. 14

Answer 1

Answer: (D)

14

Answer 2

Mean = $\frac { 1 \times 5 + 2 \times 4 + 3 \times 6 + 4 \times f } { 5 + 4 + 6 + f }$

i.e.,]$3 = \frac { 5 + 8 + 18 + 4 f } { 15 + f }$ ⇒ $45 + 3 f = 31 + 4 f$

⇒ $45 - 31 = f$ ⇒ $f = 14$.