Australia's Exports and Imports of Services by Selected Regions Exports ($m) Imports ($m) Country 2017 2018 2017 2018 Africa 1,255 1,308 1,398 1,618 Americas 12,653 14,139 19,831 21,355 Asia 48,164 53,358 33,604 37,677 Europe 13,374 14,261 23,661 25,714 Oceania and Antartica 6,075 6,453 8,198 9,135 Other 3,457 3,266 2,581 2,284 Source: Australian Government: Department of Foreign Affairs and Trade Composition of Trade Australia 2018The lecturer wishes to draw histograms in presenting graphical summaries of the data on the two main variables concerned - weekly working hours and marks attained, as stored in 'HoursMark53' worksheet. ~ (a) He decided to use 7 class intervals to construct a histogram for each variable. Explain how the lecturer could have decided in using 7 as the number of class intervals to be used. 1 mark (b) The lecturer specified class intervals 0