Excercise 8.1
Question 1:
Which is greater?
(a) 0.3 or 0.4 (b) 0.07 or 0.02
(c) 3 or 0.8 (d) 0.5 or 0.05
(e) 1.23 or 1.2 (f) 0.099 or 0.19
(g) 1.5 or 1.50 (h) 1.431 or 1.490
(i) 3.3 or 3.300 (j) 5.64 or 5.603
Answer:
(a) 0.3 or 0.4
The whole parts of these numbers are same. It can be seen that the tenth part of 0.4 is greater than that of 0.3.
Hence, 0.4 > 0.3
(b) 0.07 and 0.02
Here, both numbers have same parts up to the tenth place. However, the hundredth part of 0.07 is greater than that of 0.02.
Hence, 0.07 > 0.02
(c) 3 or 0.8
It can be seen that the whole part of 3 is greater than that of 0.8.
Hence, 3 > 0.8
(d) 0.5 or 0.05
The whole parts of these numbers are same. It can be seen that the tenth part of 0.5 is greater than that of 0.05.
Hence, 0.5 > 0.05
(e) 1.23 or 1.20
Here, both numbers have same parts up to the tenth place. However, the hundredth part of 1.23 is greater than that of 1.20.
Hence, 1.23 > 1.20
(f) 0.099 or 0.19
The whole parts of these numbers are same. It can be seen that the tenth part of 0.19 is greater than that of 0.099.
Hence, 0.099 < 0.19
(g) 1.5 or 1.50
Here, both numbers have the same parts up to the tenth place. Also, there is no digit at hundredth place of 1.5. This implies that this digit will be 0, which is same as the digit at the hundredth place of 1.50. Therefore, both these numbers are equal.
(h) 1.431 or 1.490
Here, both numbers have the same parts up to the tenth place. However, the hundredth part of 1.490 is greater than that of 1.431.
Hence, 1.431 < 1.490
(i) 3.3 or 3.300
Here, both numbers have the same parts up to the tenth place. Also, there is no digit at hundredth and thousandth place of 3.3. This implies that these digits are 0, which are the same as the digits at the hundredth and thousandth place of 3.300. Therefore, both these numbers are equal.
(j) 5.64 or 5.603
Here, both numbers have the same parts up to the tenth place. However, the hundredth part of 5.64 is greater than that of 5.603.
Hence, 5.640 > 5.603
========================================================================================================
Excercise 8.2
Question 1:
Express as rupees using decimals.
(a) 5 paise (b) 75 paise
(c) 20 paise (d) 50 rupees 90 paise
(e) 725 paise
Answer:
It is known that there are 100 paise in 1 rupee.
(a)
(b)
(c)
(d)
(e)
Question 2:
Express as metres using decimals.
(a) 15 cm (b) 6 cm
(c) 2 m 45 cm (d) 9 m 7 cm
(e) 419 cm
Answer:
It is known that there are 100 cm in 1 metre.
(a)
(b)
(c)
(d)
(e)
Question 3:
Express as cm using decimals.
(a) 5 mm (b) 60 mm
(c) 164 mm (d) 9 cm 8 mm
(e) 93 mm
Answer:
It is known that there are 10 mm in 1 cm.
(a)
(b)
(c)
(d)
(e)
Question 4:
Express as km using decimals.
(a) 8 m (b) 88 m
(c) 8888 m (d) 70 km 5 m
Answer:
It is known that there are 1000 metres in 1 km.
(a)
(b)
(c)
(d)
Question 5:
Express as kg using decimals.
(a) 2 g (b) 100 g
(c) 3750 g (d) 5 kg 8 g
(e) 26 kg 50 g
Answer:
It is known that there are 1000 grams in 1 kg.
(a)
(b)
(c)
(d)
(e)
==================================================
Excercise 8.3
Question 1:
Find the sum in each of the following:
(a) 0.007 + 8.5 + 30.08
(b) 15 + 0.632 + 13.8
(c) 27.076 + 0.55 + 0.004
(d) 25.65 + 9.005 + 3.7
(e) 0.75 + 10.425 + 2
(f) 280.69 + 25.2 + 38
Answer:
(a) 0.007 + 8.5 + 30.08
(b) 15 + 0.632 + 13.8
(c) 27.076 + 0.55 + 0.004
(d) 25.65 + 9.005 + 3.7
(e) 0.75 + 10.425 + 2
(f) 280.69 + 25.2 + 38
Question 2:
Rashid spent Rs 35.75 for Maths book and Rs 32.60 for Science book. Find the total amount spent by Rashid.
Answer:
Price of Maths book = Rs. 35.75
Price of Science book = Rs. 32.60
Total amount spent by Rashid is
Therefore, the amount spent by Rashid is Rs 68.35.
Question 3:
Radhika’s mother gave her Rs 10.50 and her father gave her Rs 15.80, find the total amount given to Radhika by the parents.
Answer:
Amount given by mother = Rs. 10.50
Amount given by mother = Rs. 15.80
Total amount given by parents is
Therefore, the amount given by her parents is Rs 26.30.
Question 4:
Nasreen bought 3 m 20 cm cloth for her shirt and 2 m 5 cm cloth for her trouser. Find the total length of cloth bought by her.
Answer:
Cloth for shirt = 3 m 20 cm
Cloth for trouser = 2 m 5 cm
Total length of cloth is
Hence, the total length of cloth bought by her is 5.25 m.
Question 5:
Naresh walked 2 km 35 m in the morning and 1 km 7 m in the evening. How much distance did he walk in all?
Answer:
Distance walked in the morning = 2 km 35 m
= 2.035 km
Distance walked in the evening = 1 km 7 m
= 1.007 km
Total distance walked by him is
Question 7:
Ravi purchased 5 kg 400 g rice, 2 kg 20 g sugar and 10 kg 850 g flour. Find the total weight of his purchases.
Answer:
Weight of rice = 5 kg 400 g =
Weight of sugar = 2 kg 20 g =
Weight of flour = 10 kg 850 g =
Total weight of his purchases is
Question 6:
Sunita travelled 15 km 268 m by bus, 7 km 7 m by car and 500 m on foot in order to reach her school. How far is her school from her residence?
Answer:
Distance travelled by bus = 15 km 268 m
= 15.268 km
Distance travelled by car = 7 km 7 m
= 7.007 km
Distance travelled on foot = 500 m
= 0.500 km
Total distance of school from her residence is
=======================================================================================================
Excercise 8.4
Question 1:
Subtract:
(a) Rs 18.25 from Rs 20.75
(b) 202.54 m from 250 m
(c) Rs 5.36 from Rs 8.40
(d) 2.051 km from 5.206 km
(e) 0.314 kg from 2.107 kg
Answer:
(a) Rs 20.75 − Rs 18.25
(b) 250 m − 202.54 m
(c) Rs 8.40 − Rs 5.36
(d) 5.206 km − 2.051 km
(e) 2.107 kg − 0.314 kg
Question 2:
Find the value of:
(a) 9.756 − 6.28
(b) 21.05 − 15.27
(c) 18.5 − 6.79
(d) 11.6 − 9.847
Answer:
(a)
(b)
(c)
(d)
Question 3:
Raju bought a book for Rs 35.65. He gave Rs 50 to the shopkeeper. How much money did he get back from the shopkeeper?
Answer:
Money that Raju will get back will be the difference of these two.
Hence, money that Raju will get back is
Therefore, he will get back Rs 14.35.
Question 4:
Rani had Rs 18.50. She bought one ice-cream for Rs 11.75. How much money does she have now?
Answer:
The money left with Rani will be the difference of these two.
Hence, the money left is
Question 5:
Tina had 20 m 5 cm long cloth. She cuts 4 m 50 cm length of cloth from this for making a curtain. How much cloth is left with her?
Answer:
The length of the cloth left with her will be the difference of these two.
Hence, the length of the cloth left with her is
Therefore, 15.55 m cloth will be remaining.
Question 6:
Namita travels 20 km 50 m every day. Out of this, she travels 10 km 200 m by bus and the rest by auto. How much distance does she travel by auto?
Answer:
Question 7:
Aakash bought vegetables weighing 10 kg. Out of this, 3 kg 500 g is onions, 2 kg 75 g is tomatoes and the rest is potatoes. What is the weight of the potatoes?
Answer:
Total weight of vegetables bought = 10.000 kg
Weight of onions = 3 kg 500 g = 3.500 kg
Weight of tomatoes = 2 kg 75 g = 2.075 kg
Weight of potatoes = Total weight of vegetables bought − (Weight of onions + Weight of tomatoes)
= 10.000 − (3.500 + 2.075)
Hence, the weight of the potatoes was 4.425 kg.