Aptitude - Clock

Exercise :: Clock - General Questions

16. 

At what time, in minutes, between 3 o'clock and 4 o'clock, both the needles will coincide each other?

A.
5 1 "
11
B.
12 4 "
11
C.
13 4 "
11
D.
16 4 "
11

Answer: Option D

Explanation:

At 3 o'clock, the minute hand is 15 min. spaces apart from the hour hand.

To be coincident, it must gain 15 min. spaces.

55 min. are gained in 60 min.

15 min. are gained in 60 x 15 min = 16 4 min.
55 11

The hands are coincident at 16 4 min. past 3.
11


17. 

How many times do the hands of a clock coincide in a day?

A. 20
B. 21
C. 22
D. 24

Answer: Option C

Explanation:

The hands of a clock coincide 11 times in every 12 hours (Since between 11 and 1, they coincide only once, i.e., at 12 o'clock).

AM

12:00
1:05
2:11
3:16
4:22
5:27
6:33
7:38
8:44
9:49
10:55

PM

12:00
1:05
2:11
3:16
4:22
5:27
6:33
7:38
8:44
9:49
10:55

The hands overlap about every 65 minutes, not every 60 minutes.

The hands coincide 22 times in a day.


18. 

How many times in a day, the hands of a clock are straight?

A. 22
B. 24
C. 44
D. 48

Answer: Option C

Explanation:

In 12 hours, the hands coincide or are in opposite direction 22 times.

In 24 hours, the hands coincide or are in opposite direction 44 times a day.


19. 

A watch which gains uniformly is 2 minutes low at noon on Monday and is 4 min. 48 sec fast at 2 p.m. on the following Monday. When was it correct?

A. 2 p.m. on Tuesday
B. 2 p.m. on Wednesday
C. 3 p.m. on Thursday
D. 1 p.m. on Friday

Answer: Option B

Explanation:

Time from 12 p.m. on Monday to 2 p.m. on the following Monday = 7 days 2 hours = 170 hours.

The watch gains 2 + 4 4 min. or 34 min. in 170 hrs.
5 5

Now, 34 min. are gained in 170 hrs.
5

2 min. are gained in 170 x 5 x 2 hrs = 50 hrs.
34

Watch is correct 2 days 2 hrs. after 12 p.m. on Monday i.e., it will be correct at 2 p.m. on Wednesday.


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