NCERT Solutions for Class 4 Mathematics Unit-2 Long And Short
NCERT Textbook Page 13
1. How Far apart are the Dots?
• Guess the distance between any two dots.
How many centimetres is it? Now measure it with the help of a scale. Did you guess right?
Ans. The guess distance between any two dots are:
A to B = 3 cm B to C = 5 cm C to D = 7cm
A to C = 3 cm B to D = 2 cm C to E = 5.5cm
A to D = 4.5cm B to E = 5 cm C to F = 2.5cm
A to E = 3.5cm B to F = 7.5cm C to G = 8cm
A to F = 4.5cm B to G = 3 cm C to H = 5cm
A to G = 5 cm B to H = 7 cm C to I = 4.5cm
A to H = 5 cm B to I = 2 cm C to J = 4cm
A to I = 2 cm B to J = 4.5cm C to K = 3cm
A to J = 1.5cm B to K = 6.5cm C to L = 6.5cm
A to K = 4 cm B to L = 2 cm C to M = 2.5cm
A to L = 3.5cm B to M =J5 cm C to N = 3cm
A to M = 5 cm B to N = 6cm C to 0 = 8cm
A to N = 3 cm B to 0=2.5cm
A to 0 = 5 cm
• Similarly guess the distances between other dots and make the The actual distances between any two dots are:
A to B = 3 cm B to C = 5.8cm C to D = 6.8cm
D to K = 7.5cm H to O = 9.5cm D to H = 9cm
G to K = 9 cm G to M = 9.6cm O to M = 10cm
O to H = 9.5cm K to H = 6cm M to H = 4.7cm
O to D = 1 cm
2. Measure the distance similarly between other dots and write them in the table.
Ans. Attempt yourself.
• Which two dots do you think are farthest from each other ? Check your answer.
Ans. Dots M and O are farthest from each other. The distance between M and O is 10
cm.
• Which two dots are nearest to each other? Check your answer.
Ans. The dots D and O are nearest to each other. The distance between D and O is 1 cm.
NCERT Textbook Page 14
1. How Birbal made Akbar’s line shorter?
Ans. Birbal drew a longer line below the line drawn by Akbar.
2. Make her right arm 1 cm longer than the left arm.
Ans.
3. Draw a cup 1 cm shorter than this cup.
Ans. The cup drawn in the figure is 1 cm shorter.
4.Draw a broom half as long as this broom.
Ans. A broom half of the size of broom given in figure is drawn here.
5. Draw another hair of double the length.
Ans. Hair of double length is shown here.
NCERT Textbook Page 15
1. Do you remember that in Class 3 you measured your height?
Ans. Yes.
2. Do you think you have grown taller?
Ans. Yes I grew taller.
3. How much?
Ans. About 6 cm.
4. Have your friends also grown taller?
Ans. Yes, most of them.
5. Find out and fill the table below.
Ans.
6. Jhumpa once read a list of the tallest people in the world. One of them was 272
cm tall! That is just double of Jhumpa’s height. How tall is Jhumpa?_________
cm.
Ans. Height of a person = 272 cm
272cm÷2 = 136 cm
Therefore, Jhumpa is 136 cm tall.
7. Could that person pass through the door of your classroom without bending?
Ans. No, because the door of our classroom is only 228 cm high.
8. Will his head touch the roof of your house if he stands straight?
Ans. Yes, because the height of my classroom is 320 cm.
9. Who is the tallest in your family?
Ans. My father is the tallest in my family. His height is 173 cm.
10. Who is the shortest in your family?
Ans. My younger brother is the shortest in my family. His height is 96 cm.
11. What is the difference between their heights?
Ans. The difference is 77 cm.
NCERT Textbook Page 16
Inter-School Sports Meet
1. Race-This is a 100 metre race for girls. Arundhati is nearest the finishing line. She is about 6 metres from it.
Behind her is Rehana. Konkana and Uma are running behind Rehana. Look at the picture. To answer the questions below choose from these distances:
— 3 metres — 6 metres
— 10 metres — 15 metres
(a) How far is Rehana from Arundhati?
Ans. Rehana is 3 metres far from Arundhati.
(b) How far ahead is Rehana from Konkana and Uma?
Ans. About 6 metres.
(c) How far are Konkana and Uma from the finishing line?
Ans. 15 metres.
2. Have you heard about a 1500 m or 3000 m race? (You remember that 1000 metres make 1 kilometre and 500 metres make half a kilometre). So you can say-
• In a 1500 metres race people run_______km.
Ans. In a 1500 metres race people run one and half km.
• In a 3000 metres race people run_______km.
Ans. In a 3000 metres race people run 3 km.
NCERT Textbook Page 17
1. Have you heard about marathon races in which people have to run about 40 kilometres? People run marathons on roads because the track of a stadium is only 400 metres.
• 10 rounds of a stadium track =_______km.
Ans. 10 rounds of a stadium track = 400 metres x 10
= 4000 metres = 4000 ÷ 1000 km
= 4 km.
• So, if you run a marathon on a stadium track, you will have to complete
rounds!
Ans. The number of rounds to be completed
= (40 x 100) ÷400 = 4000 ÷400
= 10
You have to complete 10 rounds of stadium track.
2. Dhanu has the longest jump of 3 metres 40 cm. Gurjeet is second. His jump is 20 cm less than Dhanu’s. Gopi comes third. His jump is only 5 cm less than Gurjeet’s jump.
• How long are Gurjeet’s and Gopi’s jumps?
Ans. Gurjeet’s jumps = Dhanu’s jump – 20 cm
= 3 metres 40 cm – 20 cm
= 3 metres 20 cm
Gopi’s jump = Dhanu’s jump – 5 cm
= 3 metres 40 cm – 5 cm = 3 metres 35 cm.
• Try and see how far you can jump.
Ans. I can jump one and half metre.
• How far can you throw a ball?
Ans. I can throw a ball to a distance of 5 metres.
• Look for a big ball, like a football or volleyball. How far can you kick it?
Ans. I can kick a ball to a distance of 25 metres.
NCERT Textbook Page 18
Here are the Indian Records and World Records for some jumps.
Find out from the table—
1. How many centimetres more should Chandra Pal jump to equal the Men’s World Record for high jump?
Ans. World record of high jump = 2 m 45 cm
Chandra Pal record of high jump = 2 m 17 cm
Therefore, more number of centimetres required by Chandra Pal to equal men’s high jump world record
= 2 m 45 cm – 2 m 17 cm = 28 cm.
2. How many centimetres higher should Bobby A. jump to reach 2 metres?
Ans. Bobby A. record for high jump = 1 m 91 cm
Required centimetres to reach to 2 m
= 2 m – 1 m 91 cm ,
= 1 m 100 cm – 1 m 91 cm = 9 cm.
3. Galina’s long jump is nearly
(a) 7 metres (b) 7 and a half metres
(c) 8 metres
Ans. Galina’s long jump record is 7 m 52 cm.
So, it is nearly 7 and half metres, that is option (6).
3. Look at the Women’s World Records. What is the difference between the longest jump and the highest jump?
Ans. Women’s world record for high jump = 2 m 9 cm Women’s world record for long jump = 7 m 52 cm Difference = 7 m 52 cm — 2 m 9 cm
= 5 m 43 cm.
4. If Mike P. could jump_________centimetres longer, his jump would be full 9
metres.
Ans. Record for Mike P. long jump = 8 m 95 cm
Difference to reach 9m = 9m-8m95 cm
= 5 cm.
5. Whose high jump is very close to two and half metres?
(a) Stefka K. (b) Chandra Pal
(c) Javier S. (d) Bobby A.
Ans. Javier S. high jump is 2 m 45 cm, hence it is closer to two and half metres
NCERT Textbook Page 19
Running Exercise
1. The doctor has told Devi Prasad to run 2 km every day to stay fit. He took one round of this field. How far did he run?
Ans. Devi Prasad ran one round the field
= 500 m + 500 m + 500 m + 500 m
= 2000 m
= 2000 ÷ 1000 km
= 2 km
2. The field was very far from his home. So he chose a park nearby. The boundary of the park was about 400 metres long.
• How many rounds of the park must Devi Prasad run to complete 2 km?
Ans. 2 km = 2 x 1000 m
= 2000 m
So to complete 2000 m, Devi Prasad must complete
= 2000 m ÷ 400 m
= 5 rounds
Devi Prasad has to run 5 rounds of the park.
• One day the weather was very good and cool breeze was blowing. He felt so
good that he kept jogging till he got tired after 8 rounds. That day he ran km and metres.
Ans. Devi Prasad covers a distance in 8 rounds = 400 m x 8
= 3200 m
= 3000 m + 200 m
(3000 m = 3000 ÷ 1000 = 3 km)
= 3 km 200 m
That very day he ran 3 km and 200 m.
How Many Rooms High?
1. About how many metres high is your classroom?
Ans. My classroom is about 3 metres high.
2. Guess how many rooms, one on top of the other, will be equal to the Qutub Minar?
Ans. The height of Qutub Minar = 72 m
Number of rooms one of the top of the other
= Height of Qutub Minar / Height of one room
= 72m/3m
= 24 m.
3. Explain how you made a guess.
Ans. I made a guess on the basis of the height of my classroom.
NCERT Textbook Page 20
From Kozhikode to Thalassery
1. Subodh is going to Kozhikode which is 24 kilometres (km) away. Manjani is going to Thalassery which is 46 km away in the opposite direction.
How far is Kozhikode from Thalassery?
Ans. The distance of Kozhikode from Thalassery
= Distance of Kozhikode + Distance of Thalassery
= 24 km + 46 km
= 70 km
2. Explain how you made a guess.
Ans. I made a guess on the basis of the height of my classroom.
How Far is Your Home from School?
It is only 2 km from school.
1. Momun comes to school from very far. He first walks about 400 metres to the pond. With slippers in his hands, he then walks 150 metres through the pond. Next, he runs across the 350 metres wide green field. Then he carefully crosses the 40 metres wide road to reach his school.
• How much does Momun walk every day to reach school?
Ans. Total distance of school from Momun home
= Distance of pond from his home
+ width of pond + width of green field + width of road
= 400 m + 150 m + 350 m + 40 m
= 940 m
Hence, Momun has to walk 940 m every day to reach school.
• Is it more than 1 km?
Ans. As 940 m is less than 1000 m
So, it is not more than 1 km rather it is less than 1 km.
NCERT Textbook Page 21
1. Find out how far your friends live from school and fill the table. Write in metres or kilometers.
Ans. The list of distance of school from their home is given in the table.
2. Who among you lives nearest to the school?
Ans. Sohail lives nearest to the school.
3. Who lives farthest from the school?
Ans. Rohit lives farthest from the school.
4. How many children live less than 1 km away from your school?
Ans. Me and Sohail that means two children lives less than 1 km away from school.
5. Is there anyone who lives more than 5 km away from the school?
Ans. Yes, Rohit lives more than 5 km away from school.
6. How do they come to school?
Ans. They come to the school by bicycle.
Guess and Find Out
1. How long is the thread in a reel?
Ans. The length of thread depends on the thickness of reel.
It may be 50 metres, 100 metres, 200 metres or 500 metres or more.
2. How long is the string of a kite reel? Can it be more than a kilometre long?
Ans. A kite reel may be 500 metres, 1000 metres, 2000 metres long. It can be more than a kilometer long.
3. If a handkerchief is made out of a single thread, how long would that thread be?
Ans. If a handkerchief is made out of a single thread, then the length of thread may be about 5000 metres.
NCERT Textbook Page 22
I Wish I Were
1. Which is the highest building that you have seen? About how many rooms high was it?
Ans. I saw Qutub Minar as the highest building. It is about 24 rooms high.
2. How high can a kite go? Can it go higher than the Qutub Minar?
Ans. A kite may go about upto 100 metres high. A kite can go higher than the Qutub Minar.
3. How high can a plane fly? Can it fly higher than Mount Everest which is about 9 km high?
Ans. A plane can fly more than 10000 metres high. A plane can fly higher than Mount Everest.
4. Have you ever seen clouds below you?
Ans. No. I never saw clouds below me.
