In [83]: import numpy as np

In [84]: a = np.random.randint(0, 10, 15)

In [85]: a
Out[85]: array([7, 8, 8, 6, 4, 0, 3, 0, 4, 0, 8, 0, 1, 4, 5])

In [86]: a[5:10]
Out[86]: array([0, 3, 0, 4, 0])

In [87]: a[5:10].sum()
Out[87]: 7

In [88]: a[(a >= 5) & (a <= 7)]
Out[88]: array([7, 6, 5])

In [89]: a[(a >= 5) & (a <= 7)].sum()
Out[89]: 18

In [105]: a.sum()
Out[105]: 58