Mark rolls a fair dice 48 times. How many times would Mark expect to roll a one?

Icould really use some with this question.

Which of the functions graphed below has a removable discontinuity?

Atrain leaves little? rock, arkansas, and travels north at 90 kilometers per hour. another train leaves at the same time and travels south at 80 kilometers per hour. how long will it take before they are 680 kilometers? apart?