Question

1. Find out the missing frequency for the following data if arithmetic mean is 23:
10-20
Marks
0-10
10-20
20-30
30-40
40-50
no.of students
4
8
?
6
2​

Answer 1

Marks(X) Frequency M FM

0-10 4 5 20

10-20 8 15 120

20-30 P 25 25P

30-40 6 35 210

40-55 2 45 90

N=20+P =440+25P

now, we know that

mean =m

______

N

440+25P

23= _____________

20+P

460 23P = 440 + 25 P

460-440 = 25P - 23P

20=2P

20

20

P = ____

2

ans P = 10

Explanation:

let the missing frequency P. M stand for mid value Ok ! Thank u