1.) The manager of a farmer's market has 200 lb of grain that costs \$1.90 per pound. How many pounds of meal costing \$0.80 per pound should be mixed with the 200 lb of grain to produce a mixture that costs \$1.35 per pound?
2.) A wild birdseed mix is made by combining 150 lb of millet seed costing \$0.60 per pound with sunflower seeds costing \$1.20 per pound. How many pounds of sunflower seeds are needed to make a mixture that costs \$0.75 per pound?
3.) How many gallons of a 20% acid solution must be mixed with 5 gal of a 35% acid solution to make a 23% acid solution?
4.) How many pounds of a chicken feed that is 40% corn must be mixed with 200 lb of a feed that is 90% corn to make a chicken feed that is 80% corn?
5.) An executive drove from home at an average speed of 50 mph to an airport where a helicopter was waiting. The executive boarded the helicopter and flew to the corporate offices at an average speed of 100 mph. The entire distance was 350 mi. The entire trip took 5 h. Find the distance from the airport to the corporate offices.
6.) A plane left Kennedy Airport on Tuesday morning for an 865-mile, 7-hour trip. For the first part of the trip, the average speed was 115 mph. For the remainder of the trip, the average speed was 130 mph. How long did the plane fly at each speed?