The Answer
I also have two of Einstein's puzzles, but never bothered figuring them out.
Planets Large and Small
Kate and Shireen are making a classroom model of the solar system. Mercury, the smallest planet, has a diameter of 3,000 miles. Jupiter, the largest planet, has a diameter of 88,700 miles. The girls have decided to use a pea measuring 0.5 cm in diameter as the Mercury model.
Using the same scale, what size, to the nearest whole centimeter, should the diameter of the Jupiter model be?