Look for a pattern in the following repeating sequence of letters: A B C A B C A B C .... What letter will be in the 243th position?

New York City is on eastern standard time, St Louis is on central standard time (1 hour earlier than eastern standard time), and Las Vegas is on Pacific standard time (3 hours earlier than eastern standard time). A flight leaves New York City at 9 A.M. eastern standard time, stops for 50 min in St. Louis, and arrives in Las Vegas at 1:35 P.M. Pacific time. How long is the plane actually flying ?

For a simple cubic array, solve for the volume of an interior sphere (cubic hole) in terms of the radius of a sphere in the array.

A metallic solid with atoms in a face-centered cubic unit cell with an edge length of 392 pm has a density of 21.45 $\mathrm { g } / \mathrm { cm } ^ { 3 } .$ Calculate the atomic mass and the atomic radius of the metal. Identify the metal.

Why is the index of refraction always greater than or equal to 1?