Chapter 9: Time & Speed - Practice Now 1 & 2 and Worked Example 1 & 2 - Solution

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Chapter 9: Time & Speed

FORMULAS:

• Arrival Time = Depart Time + Journey Time
• Depart Time = Arrival Time - Journey Time
• Journey Time = Arrival Time - Depart Time
• 1 hour = 60 minutes
• 1 hour = 3600 seconds
• 1 minute = 60 seconds
• 1 minute = ¹ / ₆₀ hours
• 1 second = ¹ / ₆₀ minutes
• 1 second = ¹ / ₃₆₀₀ hours

PRACTISED NOW

PRACTISE NOW 1:
A ship left port X at 22:45 on Friday and arrived at Port Y 7¹/₄ hours later. At what time and day the ship arrive at Port Y?
Solution:
Data:
Depart time: 22:45
Depart day: Friday
Journey time: 7¹/₄ hours
To change ¹/₄ hour into minute
¹/₄ x 60 = 15 minutes
Therefore
Journey time: 7 hours and 15 minutes = 7:15
Arrival time = ?
Arrival day = ?

Formula:
Arrival Time = Depart Time + Journey Time
Arrival Time = 22:45 + 7:15

Arrival time is 6:00 on next day 
Answer: The ship arrives at port Y, at 6:00 or 6:00 a.m. on Saturday.

PRACTISE NOW 2:
A bus left city P at 10:45 and arrived at city Q at 23:11 on the same day. How long was the bus journey?
Solution:
Data:
Depart time: 10:45
Arrival time = 23:11
Journey time: ?

Formula:
Journey Time = Arrival Time - Depart Time
Journey Time = 23:11 - 10:45 = 12:26

Answer: The bus journey took 12 hours and 26 minutes.

WORKED EXAMPLES

Worked Example 1:
A car leaves Town A at 21:15 on Wednesday and Town B 5 hours later. At what time and day does the car arrive at Town B?
Solution:
Data:
Departure time: 21:15
Departure day: Wednesday
Journey time: 5¹/₂ Hours.
To change ¹/₂ hour into minute
¹/₂ x 60 = 30 minutes
Therefore
Journey time: 5 hours and 30 minutes = 5:30
Arrival Time: ?
Arrival Day:?

Formula:
Arrival time = Departure time + Journey time
Arrival time = 21:15 + 5: 30

Arrival time is 2:45 on next day
Answer: The car arrives at Town B, at 2:45 or 2:45 a.m. on Thursday.

Worked Example 2:
A train left City A at 07:35 and arrived at City B at 13:05 on the same day. How long was the train journey?
Solution:
Data:
Departure time: 7:35
Arrival time: 13:05
Journey time: ?

Formula:
Journey time = Arrival time - Departure time
Journey time = 13:05 - 7:35

Answer: The train journey took 5 hours and 30 minutes.