An electronics manufacturer recorded the
battery life of some different models of mobile
phones
They have displayed some of their results in
the incomplete histogram and frequency table
below.
Use this information to work out the missing
value that completes the frequency table.
Frequency density
0.
115
20 25
Battery life (hours)
30 35
Battery life, x (hours)
15 ≤ x<20
20≤x≤22
22 ≤x≤28
28≤x≤30
Frequency
130
28
300