Ex 14.1, 3 - Daily pocket allowance of children of a locality - Ex 14.1

  1. Class 10
  2. Important Questions for Exam - Class 10
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Ex 14.1, 3 The following distribution shows the daily pocket allowance of children of a locality. The mean pocket allowance is Rs.18. Find the missing frequency f. Daily pocket allowance (in Rs) Number of workers 11 – 13 7 13 – 15 6 15 – 17 9 17 – 19 13 19 – 21 f 21 – 23 5 23 – 25 4 Class mark (xi) (11 + 13)/2 = 12 (13 + 15)/2 = 14 (15 + 17)/2 (17 + 19)/2 (19 + 21)/2 (21 + 23)/2 (23 + 25)/2 7 × 12 6 × 14 9 × 16 13 × 18 f × 20 5 × 22 4 × 24 ∑▒𝑓𝑖𝑥𝑖= 752 + 20f 18 = (752 + 20𝑓)/(44 + 𝑓) 18(44 + f) = 752 + 20f 18(44)+ 18(f) = 752 + 20f 792 + 18f = 752 + 20f 792 – 752 = 20f – 18f 40 = 2f f = 40/2 f = 20

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