The numeric is not important. This a volume problem. You need to guess size of bus wxdxh. You need to know if bus is full of passengers or not? You need to know if small or large one. Any additional data is beneficial. Golf ball size is 1x1x1 cubic in Bus volume for example is 120inx120inx144= about 2M Cu in Divide bus volume by golf ball volume = About 2M balls based on data above. GODD LUCK