Since it is asking for the ratio of 6th grade students to all you need to put the amount of 6th grade students first. Then you add the amount of 6th and 5th grade students to get 30. and so the ratio would be 10:30. Hope it helped! :)
If the snow falls at a rate of 1.3 inches per hour, dividing 6.825 into 1.3 should give you your answer. 6.825/1.3 = 5.25 Therefore, the snow was falling for 5.25 hours, or 5 hours and 15 minutes.
