Question

The standard deviation for the following data is.

• A. 26.75
• B. 24.46
• C. 25.89
• D. none

Answer 1

Answer: (C)

25.89

Answer 2

$\therefore$ The mean $= { 67.5 + \frac{\sum f_{i} u_{i }}{\sum f_i} \times 15}$ $= 67.5 + \frac{-105}{230} \times 15 =67.5 -6.85 = 60.65$ nearly. ${ S.D. = c }\times \sqrt{\frac{\sum { f_{i} u_{i }^{2}}}{\sum { f_i}} - \bigg( \frac{\sum { f_{i} u_{i }}}{\sum { f_i}} \bigg)^2}$ $= 15 \times \sqrt{\frac{733}{230} - \bigg( \frac{ - 150}{230} \bigg)^2}$ $= 15 \times \sqrt{ 3.1870 - 0.2080}$ $= 15 \times \sqrt{2.9790} = 15 \times 1.726 = 25 .890$