Overview Exercise "Example is better than precept."
- (Proverb)
11.
How many times are the hands of a clock at right angle in a day?
Answer: C
Explanation:
In 12 hours, they are at right angles 22 times.
12.
The angle between the minute hand and the hour hand of a clock when the time is 8.30, is:
Answer: B
Explanation:
Angle traced by hour hand in
17
hrs =
360
x
17
º
= 255.
2
12
2
Angle traced by min. hand in 30 min. =
360
x 30
º
= 180.
60
13.
How many times in a day, are the hands of a clock in straight line but opposite in direction?
Answer: B
Explanation:
The hands of a clock point in opposite directions (in the same straight line) 11 times in every 12 hours. (Because between 5 and 7 they point in opposite directions at 6 o'clcok only).
So, in a day, the hands point in the opposite directions 22 times.
14.
At what time between 4 and 5 o'clock will the hands of a watch point in opposite directions?
Answer: C
Explanation:
At 4 o'clock, the hands of the watch are 20 min. spaces apart.
To be in opposite directions, they must be 30 min. spaces apart.
55 min. spaces are gained in 60 min.
50 min. spaces are gained in
60
x 50
6
min.
55
11
6
min. past 4.
11
15.
At what time between 9 and 10 o'clock will the hands of a watch be together?
Answer: D
Explanation:
To be together between 9 and 10 o'clock, the minute hand has to gain 45 min. spaces.
55 min. spaces gained in 60 min.
45 min. spaces are gained in
60
x 45
1
min.
55
11
1
min. past 9.
11
In 24 hours, they are at right angles 44 times.
