Between 9 O'clock and 10 O'clock, when the times at which the minutes and hour hands be at 90° with each other are 9 hours t1, min. and 9 hours t2 min., then t2 - t1 =
1
\(\frac{{280}}{11} \)
2
\(\frac{{1080}}{11} \)
3
\(\frac{{540}}{11} \)
4
\(\frac{{360}}{11} \)