Q1.
What is the angle between the hour hand and the minute hand of a clock at 3:30?
- 75°
- 80°
- 65°
- 90°
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Answer: A. 75°
At 3:30, the hour hand is between 3 and 4, and the minute hand is at 6.
Angle of minute hand from 12 = 30 minutes * 6°/minute = 180°.
Angle of hour hand from 12 = 3 hours * 30°/hour + 30 minutes * 0.5°/minute = 90° + 15° = 105°.
The angle between them = |180° - 105°| = 75°.
Alternatively, using the formula: Angle = |(11/2)M - 30H| = |(11/2)*30 - 30*3| = |11*15 - 90| = |165 - 90| = 75°.
Q2.
If a clock shows 7:20, what time will its mirror image show?
- 4:40
- 5:40
- 4:20
- 5:20
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Answer: A. 4:40
To find the mirror image time, subtract the given time from 11:60.
11:60 - 7:20 = 4:40.
Q3.
How many times do the hour hand and the minute hand of a clock coincide (overlap) in a 12-hour period?
- 11
- 12
- 22
- 24
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Answer: A. 11
The hands of a clock coincide 11 times in 12 hours. They coincide once every hour, except between 11 and 1 o'clock, where they coincide only once (at 12 o'clock).
Q4.
A clock gains 10 seconds every hour. If it is set right at 8 AM on Monday, what time will it show at 8 AM on Wednesday?
- 8:08 AM
- 8:04 AM
- 7:52 AM
- 8:16 AM
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Answer: A. 8:08 AM
The total duration from Monday 8 AM to Wednesday 8 AM is 48 hours.
In 1 hour, the clock gains 10 seconds.
In 48 hours, the clock will gain = 48 * 10 seconds = 480 seconds.
Convert seconds to minutes: 480 seconds / 60 seconds/minute = 8 minutes.
So, when the actual time is 8 AM on Wednesday, the faulty clock will show 8 minutes past 8 AM, i.e., 8:08 AM.
Q5.
At what time between 4 and 5 o'clock will the hands of a clock be at a right angle (90 degrees)?
- 4:05 5/11 minutes
- 4:30 minutes
- 4:45 minutes
- 4:50 5/11 minutes
Show answer
Answer: A. 4:05 5/11 minutes
The formula for the angle between hands is θ = |(11/2)M - 30H|.
Here, H = 4, θ = 90°.
90 = |(11/2)M - 30*4|
90 = |(11/2)M - 120|
Case 1: (11/2)M - 120 = 90
(11/2)M = 210
M = 420/11 = 38 2/11 minutes.
Case 2: (11/2)M - 120 = -90
(11/2)M = 30
M = 60/11 = 5 5/11 minutes.
Both 4:05 5/11 minutes and 4:38 2/11 minutes are valid times. From the options, 4:05 5/11 minutes is present.
Q6.
What is the smaller angle between the hour hand and the minute hand of a clock at 10:10?
- 115°
- 120°
- 110°
- 105°
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Answer: A. 115°
At 10:10, H=10, M=10.
Angle = |(11/2)M - 30H| = |(11/2)*10 - 30*10| = |55 - 300| = |-245| = 245°.
Since the question asks for the smaller angle, we subtract this from 360°.
Smaller angle = 360° - 245° = 115°.
Q7.
How many times do the hour hand and the minute hand of a clock point in opposite directions (180 degrees) in a 24-hour period?
- 22
- 24
- 11
- 23
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Answer: A. 22
The hands of a clock point in opposite directions (180 degrees) 11 times in a 12-hour period. This happens once every hour, except between 5 and 7 o'clock, where it happens only once (at 6 o'clock).
Therefore, in a 24-hour period, they will point in opposite directions 11 * 2 = 22 times.
Q8.
A clock gains 15 minutes in every 24 hours. If it is set right at 10 AM on Monday, when will it show the correct time again?
- Sunday 10 AM
- Saturday 10 AM
- Friday 10 AM
- Thursday 10 AM
Show answer
Answer: A. Sunday 10 AM
For the clock to show the correct time again, it must gain a total of 12 hours (720 minutes).
The clock gains 15 minutes in 24 hours.
Time taken to gain 1 minute = 24/15 hours.
Time taken to gain 720 minutes = (24/15) * 720 hours = (8/5) * 720 hours = 8 * 144 hours = 1152 hours.
Convert hours to days: 1152 hours / 24 hours/day = 48 days.
So, the clock will show the correct time again 48 days after Monday 10 AM.
Monday 10 AM + 48 days = Sunday 10 AM (since 48 days is 6 weeks and 6 days, Monday + 6 days = Sunday).
Q9.
At what time between 5 and 6 o'clock will the minute hand be exactly 4 minutes ahead of the hour hand?
- 5:31 7/11 minutes
- 5:28 5/11 minutes
- 5:34 6/11 minutes
- 5:30 minutes
Show answer
Answer: A. 5:31 7/11 minutes
If the minute hand is 4 minutes ahead of the hour hand, the angle between them is 4 * 6° = 24°.
Since the minute hand is ahead, we use the formula: (11/2)M - 30H = θ.
Here, H = 5, θ = 24°.
(11/2)M - 30*5 = 24
(11/2)M - 150 = 24
(11/2)M = 174
M = 348/11 = 31 7/11 minutes.
So, the time is 5:31 7/11 minutes.
Q10.
How many times do the hands of a clock form a right angle (90 degrees) in a 12-hour period?
- 22
- 24
- 11
- 20
Show answer
Answer: A. 22
The hands of a clock form a right angle (90 degrees) twice every hour, except between 2-3 o'clock and 8-9 o'clock, where they form a right angle only once each.
So, in 12 hours, they form a right angle 22 times (24 - 2 = 22).