Final answer:
On April 21, the sun would be directly overhead at noon at a latitude between 0 degrees and 23.5 degrees N. Considering the position of the Tropic of Cancer and the vernal equinox, the closest estimate for the latitude is approximately 8 degrees N.
Step-by-step explanation:
The question is about determining the latitude where the sun is directly overhead at noon on April 21. The sun's position changes throughout the year because of the Earth's tilt and its orbit around the sun. On March 21, known as the vernal equinox, the sun is directly overhead at the Equator. Moving towards June 21, the sun shifts its direct overhead position towards the Tropic of Cancer, which is at 23.5 degrees N latitude. As April 21 falls after March 21 but before June 21, the sun would have begun its northward journey but not yet reached the Tropic of Cancer. Therefore, the direct overhead position of the sun would be at a latitude between 0 degrees and 23.5 degrees N. Without precise calculation and since the sun's declination on a specific day is not provided, the closest approximate latitude where the sun is directly overhead at noon on April 21 would be 8 degrees N, as that reflects a position north of the equator but south of the Tropic of Cancer.