Important Questions with Solutions: Racing Seconds | Mathematics (Maths Mela) Class 5 - New NCERT PDF Download

Q1: What time will it be
(a) 2 hours after 8 a.m.?
(b) 4 hours after 10 p.m.?
(c) 5 hours before 12 noon.?
(d) 4 hours before 2 a.m.?

Ans: (a) 2 hours after 8 a.m. will be 10 a.m.
(b) 2 hours after 10 p.m. will be 12 midnight.
2 hours after 12 midnight will be 2 a.m.
Thus, 4 hours after 10 p.m. will be 2 a.m.
(c) 5 hours before 12 noon will be 7 a.m.
(d) 2 hours before 2 a.m. will be 12 midnight.
2 hours before 12 midnight will be 10 p.m.
Thus, 4 hours before 2 a.m. will be 10 p.m.

Q2: Write down the time shown by each of the following clocks.
 

Ans: (a) The time is 4:35 or 25 minutes to 5.
(b) The time is 1:30 or half-past 1.  
(c) The time is 3:40 or 20 minutes to 4.
(d) The time is 6:55 or 5 minutes to 7.
(e) The time is 8:10 or 10 minutes past 8.
(f) The time is 10:40 or 20 minutes to 11.

Q3: Write the time using a.m. or p.m.
(a) 6:30 in the evening
(b) 7:15 in the morning
(c) 4:08 in the morning
(d) 45 minutes after midnight.
(e) 1: 45 after midnight.
(f) 1 hour after 12 noon

Ans: (a) 6:30p.m.
(b) 7:15a.m.
(c) 4:08a.m.
(d) 12:45 a.m.
(e) 1:45 a.m.
(f) 1:00 p.m.

Q4: How many days are there from 16th March to 12th April?

Ans: Days left out in March = 31 - 15 = 16
Days in April = 12
Total number of days = 16 + 12 = 28
So, there are 28 days from 16th March to 12th April.

Q5: Convert 12-Hours Clock to 24-Hours Clock
(a) 7: 30 p. m.
(b) 11: 55 a. m.
(c) 3: 20 p. m.
(d) 10: 00 a. m.

Note: A 12-hour clock uses the numbers 1 - 12. A 24-hour clock typically uses the number 0 - 23, where 00: 00 indicates midnight and a day runs from midnight to midnight over 24 hours.

(a) Given time is 7: 30 p. m. Now, convert into 24-hours clock:

Therefore, the answer is 19: 30.

(b) Given time is 11: 55 a. m. Now, convert into 24-hours clock:

Therefore, the answer is 11: 55.

(c) Given time is 3: 20 p. m. Now, convert into 24-hours clock:

Therefore, the answer is 15: 20.

(d) Given time is 10: 00 a. m. Now, convert into 24-hours clock:

Therefore, the answer is 10: 00.

Q6: Convert 24-Hours Clock to 12-Hours Clock

(a) 16: 30

(b) 20: 20

(c) 08: 10

(d) 15: 55

(a) Given time is 16:30.
Now, convert into 12-hours clock: Therefore, the answer is 4:30 p.m.
(b) Given time is 20:20.
Now, convert into 12-hours clock :20:20=20:20−12:00 = 8:20
Therefore, the answer is 8:20 p. m.
(c) Given time is 08:10.
Now, convert into 12-hours clock :08:10 = 08:10
Therefore, the answer is 08:10 a. m.
(d) Given time is 15:55.
Now, convert into 12-hours clock:15:55 = 15:55−12:00 =03:55
Therefore, the answer is 03:55 p. m.

Q7: Write in the Time Using A.M. - P. M. Conversion

(a) 3 hour past 04: 00 a. m. is?
(b) 1 hour past 7: 00 p.m. is?
(c) 25 minutes past 11: 40 a.m. is?
Ans:

Note: “AM” stands for anti meridiem, meaning “before midday” while “PM” stands for post meridiem, or “after noon”.

(a) Given a sentence, 3 hours past 04:00 a.m.

So, 3 hours past 04: 00 a.m. represent after 3 hours
Hence, 4:00 +3 = 7:00 

Therefore, the time 3 hour past 04: 00 a.m. is 7:00 a.m.

(b) Given a sentence, 1 hour past 7:00 p.m.

So, 1 hour past 7: 00 p.m. represent after 1 hour

Hence, 7:00 + 1 = 8:00 

Therefore, the time 1 hour past 7: 00 p. m. is 8: 00 p. m.

(c) Given a sentence, 25 minutes past 11:40 a.m. So, 25 minutes past 11:40 a.m. represent after 25 minutes

Hence, 11:40+25min = (40+25) min = 65min = 1 h 5 min=11:00+1 h 5 min
=12:05 
Therefore, the time 25 minutes past 11: 40 a.m. is 12: 05 p.m