A solar oven must heat water to at least 80 C and cost under 15 dollars to build. The table gives each team's test results. Which oven meets both criteria?

A model turbine blade set must produce at least 0.40 W and have a mass under 30 g. The table shows each set's test results. Which blade set meets both criteria?

A straw bridge must hold at least 5.0 kg and use no more than 50 straws. The table shows the test results for four bridges. Which bridge meets both criteria?

A bottle sleeve must keep water above 45 C for 30 minutes and be under 1.5 cm thick. The table shows the test results. Which sleeve meets both criteria?

An egg-drop parachute must fall for at least 4.0 s and have a canopy no wider than 40 cm. The table shows the drop-test results. Which parachute meets both criteria?

A water rocket fin set must send the rocket at least 20 m and add less than 25 g of mass. The table shows the launch results. Which fin set meets both requirements?

A gutter guard must pass at least 90% of water and block at least 80% of leaves. Guard J passed 95% and blocked 72%. Guard K passed 91% and blocked 84%. Which guard qualifies?

Wall insulation panels must cut heat loss by at least 30% and be under 3 cm thick. The table shows the test results. Which panel cuts heat loss most yet cannot be used?

A model water wheel must lift at least 500 g and cost under 10 dollars. The table shows the results. Which wheel lifts the most yet breaks a stated limit?

Rubber-band cars must travel at least 6 m with a mass under 200 g. The table shows the test results. Which car traveled farthest yet must be rejected?

Speakers must reach 70 dB and run at least 4 hours on one battery. Speaker G reached 78 dB and ran 2.5 hours. Speaker H reached 71 dB and ran 5 hours. Which speaker is louder but unusable?

Two model boats carried marbles. Hull A had a narrow bow and moved fastest, but tipped when loaded. Hull B had a wide flat bottom and stayed upright, but moved slowly. What should the team build next?

Greenhouse A has a clear plastic roof; it warmed fastest but seedlings wilted at 45 C. Greenhouse B has side vents; it never overheated but stayed too cool to sprout seeds. What should the team build next?

Filter A pours through a gravel layer: it runs fast but the water stays cloudy. Filter B pours through packed cotton: the water comes out clear but clogs after two cups. What should the team build next?

Cooler A is lined with foil and kept ice frozen longest, but crushed in a backpack. Cooler B has a rigid shell that kept its shape, but its ice melted in an hour. What should the team build?

Two paper gliders were each thrown once. Glider A flew 8.4 m and Glider B flew 8.7 m, both thrown from the same line. What should the team do before calling Glider B better?

Team A tested its wind turbine outdoors on a breezy day. Team B tested its turbine indoors in front of a fan. Team A's produced more power. What must happen before the results are compared?

A cart design must roll across a gym floor, but both prototypes were tested only on a smooth lab bench. Cart X rolled farther there. What test is still needed before Cart X is chosen?

A water filter must remove at least 90% of sediment and cost under 20 dollars. Both prototypes removed 94%, but neither team recorded what its materials cost. What should the teams do before deciding?

One egg package was dropped from 1 m and the other from 2 m. The egg dropped from 1 m survived. What should the team do before saying that package protects the egg better?