Time

 Mind Maps

Class V - maths: Time
Q) Convert 3 days into hours?

Q) We measure what using seconds, minutes, hours, days, weeks, months and years?

Q) Convert 12 minutes into seconds?

Q) In a leaf year how many days?

Q) A year has how many weeks?

Q) Add 6 hours 40 minutes to 8 hours 11 minutes?

Q) Subtract 5 hours 40 minutes from 9 hours 30 minutes?

Q) Time is measured in?

Q) A.M. stands for?

Q) P.M. stands for?

Q) 60 seconds =?

Q) 60 minutes = ?

Q) 24 hours =?

Q) How many days are there in February month and leap year?

Q) 10 hours = how many minutes?

Q) 20 minutes = how many seconds?

Q) 372 minutes = how many hours?

Q) What is the time?

Q) A week has?

Q) 100 years make a?

Q) Add 4 hours 44 minutes to 7 hours 34 minutes?

Q) Add 6 hours 30 minutes 46 seconds and 5 hours 56 minutes 23 seconds?

Q) Subtract 3 hours 45 minutes from 9 hours 23 minutes?

Q) Subtract 7 hours 34 minutes 23 seconds from 11 hours 23 minutes 11 seconds?

Q) Mary came back home from school at 2:00 pm. What time was it by the 24-hour clock?

Q) Subtract 11 hrs 25 mins 30 seconds from 20 hours?

Q) What is Time?

Q) Rahul went to the summer camp from 10th May to 7th July. How many days he spent at the camp?

Q) Majid completed his 20 days basketball coaching on 7th October. When did he join for coaching?

Q) Majid completed his 20 days basketball coaching on 7th October. When did he join for coaching?

Q) The months which have 31 days are?

Q) Ramu was given 12 hours to complete his assignment. He completed it in 9 hours 37 minutes. How much time did he save?

Q) The dinner was to begin at 7:45 p.m. Raheem reached half an hour late for the dinner. What time did Raheem reach?

Q) The summer vacation was between 20 April and 12 June. For how many days was school closed?

Q) The college opened 20 days before Rushi's birthday on 21 June. On which day did the school open?

Q) Suma goes to school at 9:30 a.m. and comes back home at 5:00 p.m. How many hours does she spend in school?

Q) What is addition and subtraction of time and give an examples?

Q) What is remembering days by the calendar and give an examples?

Q) Raj went to the market to buy some clothes, he went at 11 : 00 a.m. and came back at 2 : 00 p.m. How many hours he spent in the market?

Q) Add 6 hours 75 minutes and 4 hours 25 minutes,we get

Q) Convert the 12 minutes into seconds?

Q) Add 10 hrs 35 minutes 25 seconds and 8 hrs 30 minutes 45 seconds.

Time

Definition

"Time is the ongoing sequence of events taking place. The past, present and future. We measure time using seconds, minutes, hours, days, weeks, months and years".

• Time is measured in a.m. or p.m. where a.m. stands for 'ante meridian' and p.m. stands for 'post meridian'.
• For the timings after 12 o' clock midnight, a.m. is used.
• For the timings after 12 o'clock noon, p.m. is used.
• The smallest measure of time is the second.
• 60 seconds = 1 minute
• 60 minutes = 1 hour
• 24 hours = 1 day.

Example:

As we can see in the figure above, the hours hand is at 3 and the minutes hand is at 12.
So, the time is 3 O' clock.

Converting Bigger Units Of Time Into Smaller Units

Let us consider table for converting hours, minutes and seconds.

CONVERTING DAYS INTO HOURS CONVERTING HOURS INTO MINUTES CONVERTING MINUTES INTO SECONDS
1 DAY = 24 HOURS 1 HOUR = 60 MINUTES 1 MINUTE = 60 SECONDS
To convert days into hours,
multiply the number of
days by 24.
To convert hours into minutes,
multiply the
number of hours by 60.
To convert minutes into seconds,
multiply the number
of minutes by 60.
5 days = (5 x 24)
hours =120 hours
Example:
5 days 2 hours
= (5 x 24) hours + 2 hours
= 120 hours + 2 hours
=122 hours.
10 hours = (10 x 60)
minutes = 600 minutes
Example:
6 hours 12 minutes
= (6 x 60) min + 12 min
= 360 min + 12 min
= 372 minutes
20 minutes = (20 x 60)
seconds = 1200 seconds
Example:
3 minutes 40 seconds
= (3 x 60) seconds + 40 sec
= 180 sec + 40 sec
= 220 seconds
Converting Smaller Units Of Time Into Bigger Units
THE 24 - HOUR CLOCK

The 24-hour clock is used in places where work is done by people round the clock.
Example: Railways, Airlines etc.

• Time in the 24-hour clock is written in 4- digits.
• The first two digits on the left are for the hours and the two digits on the right are for the minutes. There is no dot separating the four digits.
• 12 O' clock midnight is expressed as '0000' hours.
• 12 O' clock at noon is expressed as 1200 hours.

#### Converting The 12 Hour Clock Time To 24 Hour Clock Time

• For a.m. timings, write hours and minutes side by side without separating them, write hours as a two digit number.
• For p.m. timings, add 12 to the hours and then write hours and minutes together without separating them.

• Two digits on the left are for hours and two digits on the right are for minutes. No dot is used to separate hours from minutes.

#### Converting 24 Hour Clock Time To 12 Hour Clock Time

• 1200 hours is subtracted from the 24 hour clock time when more than 1200 hours is shown. Write p.m. next to it.
• Write hours and minutes side by side by separating them with dots when less than 1200 hours or 1200 hours is shown. Write a.m. next to it.

Examples:

1. Add 6 hours 40 minutes to 8 hours 11 minutes.
Solution:

2. Add 9 hours 45 minutes to 4 hours 35 minutes.
Solution:

Since, 60 minutes = 1 hour, we regroup 80 minutes as 1 hour 20 minutes.
So, 13 hours 80 minutes = 14 hours 20 minutes.
3. Subtract 5 hours 40 minutes from 9 hours 30 minutes.
Solution:
Since, 30 is less than 40, regroup hours and minutes.
9 hours = 8 hours 60 minutes.
Add 60 minutes to the column, we have
9 hours 30 minutes = 8 hours 90 minutes.

4. Raj went to the market to buy some clothes, he went at 11 : 00 a.m. and came back at 2 : 00 p.m. How many hours he spent in the market.
Solution: 11: 00 to 12 : 00 noon = 1 hour
12 : 00 noon to 2 : 00 pm = 2 hours
So, he spent 3 hours in the market.

REMEMBERING DAYS BY THE CALENDAR
• A year has 365 days.
• In a leap year there are 366 days.
• A leap year comes after 4 years
• A week has 7 days
• 14 days make a 'Fortnight'.
• The months which have 31 days are:
• January, March, May, July, August, October, December.

• The months which have 30 days are:
• April, June, September, November.
• The month of February has 28 days, but in a leap year it has 29 days.
• 100 years make a 'Century'.
• There are 52 weeks in a year.

Have a look at the weeks and days in the following calendar.

Examples:

1. Rahul went to the summer camp from 10th May to 7th July. How many days he spent at the camp.
Solution: To find the number of days, we will count:
10th May - 31th May = 21 days (31 - 10 = 21)
1th June - 30th June = 30 days
1th July to 7th July = 7 days
Since he went to the summer camp on 10 May, the starting day will also be added to the total number of days.
Total number of days spent in the camp = 21 + 30 + 7 + 1 = 59 days.

2. Majid completed his 20 days basketball coaching on 7th October. When did he join for coaching?
Solution: Completion date = 7 October
Duration of coaching = 20 days
We have to count back 20 days from 7th October.
7th October to 1th October = 7 days
30th September to 18th September = 13 days
7 days + 13 days = 20 days.
So, Majid joined the coaching classes on 18th October.

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