Find the missing frequency from the following data. When mean is 34 Marks- 0-10 10-20 20-30 30-40 40-50 50-60 No. of students – 5

1 thought on “Find the missing frequency from the following data. When mean is 34 Marks- 0-10 10-20 20-30 30-40 40-50 50-60 No. of students – 5”

1. Step-by-step explanation:

   ClassFrequency (fi)Cumulative Frequency (cf)0 – 105510 – 20253020 – 30xx+3030 – 4018x+4840 – 507x+55

   Median is 24 which lies in 20 – 30

   ∴ Median class = 20 – 30

   Let the unknown frequency be x.

   Here, l = 20,

   n2=x+552

   , c.f. of the preceding class = c.f = 30, f = x, h = 10

   Now,

   Median,

   M=l+n2−cff×h

   ⇒24=20+x+552−30x×10

   ⇒24=20+x+55−602x×10

   ⇒ 24 = 20 +

   x−52x

   × 10

   ⇒ 24 = 20 +

   5x−25x

   ⇒ 24 = 20+

   5x−25x

   ⇒ 24x = 25x – 25

   ⇒ –x = – 25

   ⇒ x = 25

   Hence, the unknown frequency is 25.

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