+466 A racecourse goes 200 miles up a hill and then 160 miles down the other side. If Marjorie drives up the hill at 50mph, how fast must she drive down the hill to average 60mph for the whole race?
+129847 Note the total distance = 360 miles
So....at an average of 60 mph...it will take her 360/60 = 6 hours total
The uphill part takes 200/50 = 4 hours
And.......the downhill part must be covered in the other 2 hours......so....
160 / 2 = 80 mph is what she must average on the downhill part to have an overall average of 60 mph
+129847 Note the total distance = 360 miles
So....at an average of 60 mph...it will take her 360/60 = 6 hours total
The uphill part takes 200/50 = 4 hours
And.......the downhill part must be covered in the other 2 hours......so....
160 / 2 = 80 mph is what she must average on the downhill part to have an overall average of 60 mph
