Refer to the following distribution of commissions: monthly commissions class frequencies$600 up to $800 3800 up to 1,000 71,000 up to 1,200 111,200 up to 1,400 121,400 up to 1,600 401,600 up to 1,800 241,800 up to 2,000 92,000 up to 2,200 4for the preceding distribution, what is the midpoint of the class with the greatest frequency?

Aturning operation is performed with following conditions: rake angle of 12°, a feed of 0.35 mm/rev, and a depth of cut of 1.1 mm. the work piece is aluminum alloy 6061 with t6 heat treatment (a16061-t6). the resultant chip thickness was measured to be 1.0 mm. estimate the cutting force, fc. use shear stress of 207 mpa and coefficient of friction on the tool face of 0.6.