Question

For the grouped data below, find the 70th percentile (P₇₀):
Marks: 0-10, 10-20, 20-30, 30-40
No. of Students: 5, 9, 13, 3

पर्याय

• 18.5

• 25.4

• 22.2

• 28.6

Answer 1

25.4

Explanation: 
n = 30, position = 70×30/100 = 21 = 70×30/100 = 21st item. Cumulative: 5, 14, 27, 30. 21st falls in 20-30:
l = 20, cf = 14, f = 13, h = 10; P₇₀ = 20 + (21 − 14) / 13 × 10 = 20 + (7 / 13) × 10 ≈ 25.4.