192. Crossed lines


In the diagram are 4 lines, none parallel, resulting in 6 points of intersection.  If 7 additional lines are drawn, to make a total of 11 lines, none parallel, determine the number of points of intersection.  (Assume only two lines intersect at any one point.)


191. Iron truss bridge

Train on bridge at Worcester, England - DSCF0803
A train of length 160 m is traveling at a speed of 20 ㎧ (metres per second).  The train begins to cross an iron truss bridge of length 120 m.  Determine how many seconds it takes the train to cross the bridge.


190. Sliced pepperoni


The top of a cylinder with radius 3 cm is sliced at an angle, as shown in the diagram.  Determine the volume of the resultant solid.