时钟 - 例题解析

答案 - B

解释

Point followed by hour hand in 12 hours=360°. 

Point followed by hour hand in 275/60 hrs 
i.e. 55/12 hours 
= (360/12*55/12)
= (275/2)° 

Angel followed by min, hand in 60 min =360°
Angel followed by min, hand in 35 min= (360/60*35)° = 210°

Required angle = (210°-275°/2) = 145°/2

答案 - A

解释

At 3 o'clock, the hour hand is at 3 and the moment hand is at 12. 
Consequently, they are 15 minutes spaces separated. 

To be as one, the moment hand must pick up 15 minutes 
throughout the hour hand. 

55 Min. are picked up by min. hand in 60 min. 
15 min. will be picked up by it in (60/55*15) min. = 180/11 min. 

Subsequently the hand will match at 180/11 min. past 3.

答案 - A

解释

At 7 o'clock, the hour hand is at 7 and the moment hand is at 12.
In this manner, The two hands are 25 min. spaces separated. 

To be in the same straight line yet not together, 
they will be 30 min. spaces separated. 

∴ The moment hand will pick up (30-25) min.
=5 min. spaces over the hand. 
55 min. spaces are gained by hr. hand in 60 min. 

5 min. spaces will be picked up by hr. hand in (60/55*5) min. 
=60/11min. 

∴ The hands will be in the same straight line 
however not together at 60/11 min. past 7. 

答案 - B

解释

In a right clock, the moment hand picks up 55 min. 
Spaces throughout the hour hand in an hour. 
To be as one once more, 
the moment hand must increase 60minutes over the hour hand. 

55 min. are picked up in 60 min.1 
60 min. are picked up in (60/55*60) = 716/11 min. 

Be that as it may, they are as one after 65 min. 
∴ pickup in 65 min.(716/11-65)= 5/11 min. 
Pick up in 24 hours= (5/11*1440/65) min. 
∴ the clock picks up =440/43 min. in 24 hours.

答案 - C

解释

Time from 8a.m on Sunday to 8p.m on taking after Sunday 
= 7 days 12 hours = 180 hours 

∴ the watch increases (5+29/5) min. 
on the other hand 54/5 min. in 180 hrs. 

Presently 54/5 min. are picked up in 180 hrs. 
∴ 5 min. are picked up in (180*5*5/54) hrs.
= 83 hrs. 20min. 
= 3days 11 hrs and 20 min. 

∴ Watch is right 3 days 11 hrs and 20 min. after 8 am of Sunday. 
∴ it will be right at 20 min. past 7 p.m on Wednesday.