Find the variance and standard deviation of Marks- 20-30, 30-40, 40-50, 50-60, 70-80, 80-90

Question

Find the variance and standard deviation of

Marks	20-30	30-40	40-50	50-60	60-70	70-80	80-90
number of students	3	6	13	15	14	5	4

Answer 1

  

Standard Deviation (a) = \(\sqrt {variance} = \sqrt{223.22} = 14.94\)