Answer:
44,160,000 mg/hr
Step-by-step explanation:
If the lawn is 20 feet wide by 20 feet long this is 400 square feet.
on each of these 400 square feet in one minute are 1150 new snow flakes which makes 460,000 in total.
If each snowflake weighs 1.60 mg then 460,000 is 736,000 mg. But this is only per minute.
60 minutes in an hour is 44,160,000 mg of new snowflakes on that lawn in one hour.