Question

Calculate mean deviation by mean from following data:
Mark's:
5
15
25
35
45
Number of students:
15
10
40
20
75​

Answer 1

Answer:

9

Xi  f  c.f ∣Xi−M∣  fi×∣Xi−M∣

5  5  5  20  100

15  10  15  10 100

25  20  35 (Median Class)  0  0

35  5  40  10  50

45  10  50  20  200

∑fi∣Xi−M∣ =450

Rank of Median = 2N​th Observation and (2N​+1) th observation

=25th and 26th observations

Median = 225+25​ =25

Mean Deviation about Median = N1​∑fi∣Xi−M∣ = 5450​ =9