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At 40 past 4 in the evening, the smaller angle between the hour and minute hands of a clock is :

  • A.85°
  • B.90°
  • C.95°
  • D.100°

Answer: D

The smaller angle is 100°.

The angle between the hands at H hours M minutes is \(|30H - 5.5M|\):

\[ \begin{aligned} |30 \times 4 - 5.5 \times 40| &= |120 - 220| \\ &= 100^\circ \end{aligned} \]

At 4:40 the minute hand points at 8 (240°) and the hour hand has moved two-thirds of the way from 4 to 5 (140°), so they are 100° apart. Forgetting the hour hand's movement gives 120°, which is not offered.

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