1. A gas cylinder has two vents, V1 and V2, for discharge. The cylinder empties in 7  minutes when only vent V1 is open. The cylinder empties in 4  minutes when both vent V1 and vent V2 are open. About how many minutes will the cylinder take to empty if only vent V2 is open?   3.00   2.55   9.33   cannot be determined   0.33   Hint Half-n-half Clue   2. Mr. Haqim drove from Hat Hill to Capsville in 80  minutes at an average speed of 50  miles per hour. In about how many minutes should he make the return journey so that his average speed for the entire journey is 60  miles per hour?   cannot be determined   96   112   53   133   Half-n-half Clue   3. Of the S students enrolled in a Programming Course, 80% take the Certification Examination. 40% of the students who take the Certification Examination pass it. In this Certification Examination, students who pass the examination are what percent of the students enrolled in the Programming Course?   0.32 S   0.40 S   80   40   32   Half-n-half Clue   4. If a is an odd number and b is an even number, then which of the following must be an even number ?   2b + a   ab + 1   2a + b   a + b + 2   a + b   Half-n-half Clue