Aspacecraft is in a 400-km by 600-km leo. how long (in minutes) does it take to coast from the perigee to the apogee?

To solve this problem we will use Kepler's third law for which the period is defined as

The perigee altitude is the shortest distance between Earth's surface and Satellite.

The average distance of the perigee and apogee of a satellite can be defined as

Here,

R = Radius of Earth

= Lower orbit

= Higher orbit

Replacing we have,

Time Taken to fly from perigee to apogee equals to half of orbital speed is

Replacing,

Therefore will take around to 47 min and 12.8s to coast from perigee to the apogee.

the answer would be   dignified - apex

powerful computers now, not then