1.) In 3 1/2 hours 
2.) Counterfeit money
3.) As the tide rises so does the rope.
4.) Math isn't my forte
5.) Its impossible to guess three fruits correctly. 10
6.) Tomatoes
7.) Start with prepositions.
8.) Too much math.
9.) Deadman in the desert drew the shortest straw.
10.) Two answers. Ask the first guard if he is a liar. Then ask the other one if the other is the liar.