Question

Question 6 Find the mean and standard deviation using short-cut method.

xi 60 61 62 63 64 65 66 67 68

fi 2 1 12 29 25 12 10 4 5

Class X1 - Maths -Statistics Page 371

Answer 1

Here, we get,
$\sum{f_i}=100\\\sum{f_id_i}=0\\\sum{f_id_i^2}=286$
now,
we know,
$Mean(\overline{x})=A+\frac{\sum{f_id_i}}{\sum{f_i}}\\\\=64 + \frac{0}{100}=64$
$now, SD(\sigma)=\sqrt{ \frac{\sum{f_id_i^2}}{\sum{f_i}}-( \frac{\sum{f_id_i}}{\sum{f_i}})^2}\\\\=\sqrt{\frac{286}{100}-(0)^2}=\sqrt{2.86}=1.69$

Answer 2

Step-by-step explanation:

Smplity: (29 x64'y (62s'xi) (write the mswer in expements