Question

What fraction of a clockwise revolution does the hour hand of a clock turn through, when it goes from a) 5 to 11? b)2 to 8? c)10 to 1?

Answer 1

Answer: 1/2, 1/2, 1/4

Explanation:

To find the fraction that the hour hand turns of a clockwise revolution, we have to find how long it is going then divide by 12

Ex. a) 11 - 5 = 6, 6/12 = 1/2 so the hour hand turns by 1/2 of a clockwise revolution

b) 8 - 2 = 6, 6/12 = 1/2 so the hour hand turns by 1/2 of a clockwise revolution

c) For this, we have to convert 1 into 13 as 1 - 10 is a negative number

13 - 10 = 3, 3/12 = 1/4 so the hour hand turns by 1/4 of a clockwise revolution

Answer 2

The answers are :

a) 1/2

b) 1/2

c) 1/4

To find the fraction of a clockwise revolution, take the ratio between hours covered and hours covered in one revolution.

a)

• Hours covered between 5 and 11 ⇒ 11 - 5 = 6
• Hours covered in 1 revolution ⇒ 12
• 6/12 = 1/2

b)

• Hours covered between 2 and 8 ⇒ 8 - 2 = 6
• Hours covered in 1 revolution ⇒ 12
• 6/12 = 1/2

c)

• Hours covered between 10 and 1 ⇒ 13 - 10 = 3 (∴ 12 + 1 = 13)
• Hours covered in 1 revolution ⇒ 12
• 3/12 = 1/4