$ ipython --version
6.1.0
$ jupyter --version
4.3.0
$ python --version
Python 3.6.2 :: Anaconda custom (64-bit)

import numpy as np
np.__version__

'1.16.4'

import numpy as np
a = np.array([[10, 20], [60, 80]])
mean = np.mean(a)
print("平均: ", mean)
print("分散: ", np.var(a))
print('--- 手動計算 ---')
var_result = sum([(x-mean)**2 for x in a.ravel()]) / len(a.ravel())
print("分散: ", var_result)

平均:  42.5
分散:  818.75
--- 手動計算 ---
分散:  818.75