Suppose we want to choose 2 objects, without replacement, from the 4 objects pencil, eraser, desk, and chair. (a)
How many ways can this be done, if the order of the choices is taken into
consideration?

How many ways can this be done, if the order of the choices is not taken into
(b) consideration?

Two trains leave a station on different tracks. the tracks make an angle of 130°, with the station as a vertex. the first train travels 100 km and makes its first stop at point a, while the second train travels 200 km and makes it first stop at point b. how far apart are the trains when both are at their first stop? round the answer to the nearest integer. a) 65 km b) 139 km c) 224 km d) 275 km