The frequency table below shows the percentages obtained in a Biometry test for a random sample of 60 students:

Interval fi xi F
[30 – 40) 5 b1 c1
[40 – 50) 12 b2 c2
[50 – 60) 18 b3 c3
[60 – 70) 15 b4 c4
[70 – a1) 7 b5 c5
[a1 – 90) 2 b6 c6
[90 – 100) 1 b7 c7


For the percentages obtained, find the range.

a)70


b)60


c)80


d)100