Which is the best estimate for (6.3x 10^-2)(9.9x 10^-3) written in scientific notation? A. 6x10^-4
B. 60 x 10^-5
C. 6x 10^7
D. 60 x 10^6

The 40th parallel of north latitude runs across the united states through philadelphia, indianapolis, and denver. at this latitude, earth’s radius is about 3030 miles. the earth rotates with an angular velocity of latex: \frac{\pi}{12} π 12 radians (or 15°) per hour toward the east. if a jet flies due west with the same angular velocity relative to the ground at the equinox, the sun as viewed from the jet will stop in the sky. how fast in miles per hour would the jet have to travel west at the 40th parallel for this to happen? show your work and explain your process.