fambrini wrote:Did it take Ann more than 2 hours to walk a distance of 10 miles along a certain trail? (1 mile = 1.6 kilometers)
1) Ann walked this distance at an average rate of less than 6.4 kilometers per hour.
2) On average, it took Ann more than 9 minutes per kilometer to walk the distance.
OA: D
(10 miles)/(2 hours) = 5 miles per hour.
Thus, if Ann traveled at 5 mph, it took her exactly 2 hours to travel 10 miles.
Implication:
If her speed was LESS THAN 5 MILES PER HOUR, it took her MORE THAN 2 HOURS.
(5 miles)/(1 hour) * (1.6 kilometers)/(1 mile) = 8 kilometers per hour.
Question stem, rephrased:
Was Ann's speed less than 8 kph?
Statement 1:
6.4 kph is less than 8 kph.
SUFFICIENT.
Statement 2:
(1 kilometer)/(9 minutes) * (60 minutes)/(1 hour) = 6.67 kilometers per hour.
Thus, a rate of 6.67 kph allows Ann to travel 1 kilometer in 9 minutes.
Since she took MORE than 9 minutes, her rate must have been LESS THAN 6.67 kph.
Thus, her speed was less than 8 kph.
SUFFICIENT.
The correct answer is
D.
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