Frequency Table

Make a table like this.
Name the columns
Interval, Tally, and Frequency.

It says
use 5 intervals starting from 50-59.

So write the intervals
50-59, 60-69, 70-79, 80-89, and 90-99.

Find the values in 50-59.

There are,
56 and 52
two values.

So draw two tallies
in the Tally column.

And write 2
in the Frequency column.

While counting the values,
mark the values like this.

Find the values in 60-69.

There are,
60, 69, and 67,
three values.

So draw three tallies
in the Tally column.

And write 3
in the Frequency column.

While counting,
mark the values like this.

Find the values in 70-79.

There are,
74, 78, 77, 75, 70, 74, and 74,
seven values.

So draw seven tallies
in the Tally column.

And write 7
in the Frequency column.

Find the values in 80-89.

There are,
81, 81, 85, 84, 80, and 88,
six values.

So draw six tallies
in the Tally column.

And write 6
in the Frequency column.

The remaining values are the values in 90-99.

There are,
91 and 97,
two values.

So draw two tallies
in the Tally column.

And write 2
in the Frequency column.

So this is the frequency table
of the given data.

The values less than 80 are
in these three intervals:
50-59, 60-69, and 70-79.

So the number of these values is,
add the frequencies of these intervals,
2 + 3 + 7.

2 + 3 = 5

5 + 7 = 12

So there are 12 values
that are less than 80.