Rewrite the data as an ordered series. To do this we need to think how we do this with ranges. Each range covers 4 classes. With a frequency of 6 we could have, for example, 1 2 3 4 4 4. So since the class is a whole number, we have to repeat values, giving us up to 3 of one value, or 1 2 2 3 4 4.
Take the range 5-8, we have a frequency of 10 over 4 values. We could have 5 5 5 6 6 7 7 7 8 8 or we could have 5 6 6 6 6 7 7 7 7 8. There are two modes in the latter group. Looking at the group as a whole we would have to say that mode is likely in this group because we are distributing 10 data in a range of 4. So 5-8 contains at least one mode and it is likely to be higher than in the other groups.
We can't determine the mode itself absolutely without listing thr discreet data values.