Data Sufficiency

Explanation needed

In half hour, Carlos could have traveled greater than 6 miles only if his speed was greater than 12 mph.
1 mile = 5280 ft.
Thus 12 miles = 63360 ft = 17.6 ft / sec.
Stmt 1) Avg speed is greater than 16 : NOT SUFFICIENT
Stmt 2) Avg speed is less than 18 : NOT SUFFICIENT
Stmt 1 & 2) Avg speed is 16 < s < 18. : STILL NOT SUFFICIENT.

Answer E

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