Why is random sampling and random assignment in experimental research important?

Solar cell a produces 100 joules of energy, when a light source is shown on it for 3 minutes. solar cell b produces 200 joules of energy when the same light source is shown on it for 5 minutes. which solar cell works better? a) solar cell b, because it produces more energy. b) solar cell b, because it generates more power. c) solar cell a, because it produces energy quicker. d) solar cell a, because it generates a greater wattage. eliminate

Find the dimensions and area of the largest rectangle that can be inscribed in the upper half of the ellipse. (give your answers in terms of a and b. enter the dimensions as a comma-separated list.)

The mass of the sun is 1.99×1030kg and its distance to the earth is 1.50×1011m. what is the gravitational force of the sun on the earth?