EX.6. At what time between 5.30 and 6 will the hands of a clock be at right angles?
Explanation:
At 5 o'clock, 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
EX.7. At what time between 7 and 8 o'clock will the hands of a clock be in the same straight line but, not together?
Explanation:
When the hands of the clock are in the same straight line but not together, they are 30-minute spaces apart.
At 7 o'clock, they are 25 min. spaces apart.
∴ Minute hand will have to gain only 5 min. spaces.
55 min. spaces are gained in 60 min.
5 min. spaces are gained in
EX.8. At 3:40, the hour hand and the minute hand of a clock form an angle of:
(A) 1250
(B) 1200
(C) 1350
(D) 1300
Explanation:
Angle traced by hour hand in 12 hrs. = 360°.
Angle traced by it in
Angle traced by minute hand in 60 min. = 360°.
Angle traced by it in 40 min. =
∴ Required angle (240 - 110)° = 130°
EX.9. At what angle the hands of a clock are inclined at 15 minutes past 5?
Explanation:
Angle traced by hour hand in
Angle traced by min. hand in 15 min. =
EX.10. The angle between the minute hand and the hour hand of a clock when the time is 4.20, is:
(A) 100
(B) 00
(C) 200
(D) 50
Explanation:
Angle traced by hour hand in
Angle traced by min. hand in 20 min. =
∴ Required angle = (130 - 120)° = 10°
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