A telephone user while talking to a person via a satellite has to wait for reply for about __________ millisecond.

ANS:D - 540

Double hop may have 540.

But double hop means two times satellite to earth and the question doesn't define this. For single-hop transmission(outgoing and receiving).

We have calculated earlier distance b/w earth to satellite is 36000km and here we have taken 36000*2 = 72000km.

Hence 240 ms is right.