Page 133 - Math Skill - 5

Time and Temperature 131

2. Convert into 24-hour clock time.
(a) 7:20 a.m. (b) 11:59 p.m. (c) 6:45 a.m.

(d) 2:10 p.m. (e) 5:50 p.m. (f) 10:37 a.m.
3. Given below is an extract from an Airline Time-Table.

Indigo SpiceJet Air India

Delhi A 0005 D 1220 A 1835
Kolkata D 0045 A 1305 D 1930
Pune A 0125 A 1407 D 2015

A → arrival, D → departure
Read the table carefully and answer the following in a.m. or p.m.

Fact-o-meter
(a) When does the Indigo flight arrive � 1 hour = 60 minutes
at Delhi? � 1 minute = 60 seconds

(b) When does the Air India flight leave � 1 day = 24 hours
Kolkata? � 1 week = 7 days
� 1 fortnight = 2 weeks = 14 days
(c) When does the SpiceJet flight arrive � 1 year = 12 months = 52 weeks
at Pune? � 1 year = 365 days and 6 hours
� 1 leap year = 366 days

Adding and Subtracting Time and Days
The conversion of time table is as follows:
To add or subtract time, we keep the hours, minutes and seconds in separate columns and then
add. The short form of hour is ‘h’, minute is ‘min’ and second is ‘s’.

Let’s learn through examples.

Let’s Attempt

Example 1: Add 4 h 32 min 15 s and 3 h 21 min 35s.
Solution: Write h, min and s in separate columns and then add. h min s

Step 1: Add 15 s + 35 s = 50 s 1
4
Step 2: Add 32 min + 21 min = 53 min + 3 3 2 1 5
2
1
5
3
Step 3: Add 4 h + 3 h = 7 h 7 5 3 5 0
Hence, the required sum is 7 h 53 min 50 s.
h min s
Example 2: Subtract 2 h 35 min 49 s from 5 h 29 min 30 s.

Solution: Step 1: 30 – 49 is not possible, so borrow 1 min = 60 s 88
28
90
from min. column 4 29 30
5
⇒ 60 s + 30 s = 90 s – 2 35 49
⇒ 90 s – 49 s = 41 s 2 53 41