At what time between 5.30 and 6 will the hands of a clock be at right angles?
At 5 oclock, the hands are 25 min. spaces apart.
To be at right angles and that too between 5.30 and 6, the minute hand has to gain (25 + 15) = 40 min. spaces.
55 min. spaces are gained in 60 min.
40 min. spaces are gained in$ \left(\dfrac{60}{55} \times 40\right) $min=43$ \dfrac{7}{11} $min.
$\therefore$ Required time = 43$ \dfrac{7}{11} $min. past 5.