The lengths of a number of slow worms were measured, to the nearest mm. The results are shown in the table. a Work out how many slow worms. were measured. b Find the interquartile range for the lengths of the slow worms. Lengths of slow worms (mm) 125-139 140-154 Frequency 4 4 155-169 2 170-184 7 185-199 20 200-214 24 215-229 10 AppendixLO1