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Exercise 1.5

7th Maths : Term 2 Unit 1 : Number System : Exercise 1.5 : Miscellaneous Practice problems, Challenge Problems, Text Book Back Exercises Questions with Answers, Solution

Exercise 1.5

Miscellaneous practice problems

1. Write the following decimal numbers in the place value table.

(i) 247.36

(ii) 132.105

2. Write each of the following as decimal number.

i) 300 + 5  +  7/10 +   9/100 +    2/1000 = 305792

ii) 1000 + 400 + 30 + 2 +   6/10 + 7/100 = 143267

3. Which is greater?

(i) 0.888 (or) 0.28

The whole number parts of the two decimal numbers are equal.

Comparing the digits of tenth place, 8 > 2

So, 0.888 > 0.28

The greater number is 0.888.

(ii) 23.914 (or) 23.915

The two numbers have same digits upto hundredth place.

But the thousandth place of 5 > 4.

So, 23.915 > 23.914

The greater number is 23.915.

4. In a 25 m swimming competition, the time taken by 5 swimmers A, B, C, D and E are 15.7 seconds, 15.68 seconds, 15.6 seconds, 15.74 seconds and 15.67 seconds respectively. Identify the winner.

The time taken by 5 swimmers A, B, C, D and E are 15.7, 15.68, 15.6, 15.74, 15.67 seconds.

The whole parts of the two decimal numbers are equal.

So, Comparing the tenth place, 6 < 7

The numbers which have 6 in the tenth places are 15.68, 15.6, 15.67.

Comparing the hundred the place,

0 < 7 < 8

So, 15.6 < 15.67 < 15.68

The smaller decimal number is 15.6.

The swimmer who takes less time is the winner.

So, the winner is C (15.6 seconds)

5. Convert the following decimal numbers into fractions.

(i) 23.4

23.4 = 23 + ( 4÷2 / 10÷2 ) = 23 + 2/5

= 23 (2 / 5) = 117 / 5

(ii) 46.301

46.301 = 46 +   (301 / 1000)

= 46301 / 1000

6. Express the following in kilometres using decimals.

(i) 256 m

(ii) 4567 m

i) 256 m = 256/1000 km = 0.256 km

ii) 4567 m = 4567/1000 km = 4.567 km

7. There are 26 boys and 24 girls in a class. Express the fractions of boys and girls as decimal numbers.

Number of boys = 26

Number of girls = 24

Total students = 50

Boys = 26×2 / 50×2 = 52 / 100 = 0.52

Girls = 24×2 / 50×2 = 48 / 100 = 0.48

Challenge Problems

8. Write the following amount using decimals.

(i) 809 rupees 99 paise

= 809 +   99/100 = ₹809.99

(ii) 147 rupees 70 paise

= 147 +   70/100 = ₹ 147.70

9. Express the following in metres using decimals.

(i) 1328 cm

(ii) 419 cm

i) 1328 cm = 1328 / 100 m = 13.28 m

ii) 419 cm = 419 / 100 m = 4.19 m

10. Express the following using decimal notation.

(i) 8 m 30 cm in metres

8 m 30 cm = 8.30 m

(ii) 24 km 200 m in kilometres

24 km 200 m = 24.200 km

11. Write the following fractions as decimal numbers.

(i) 23 / 10000 = 0.0023

(ii) 421 / 100 = 4.21

(iii) 37 / 10 = 3.7

12. Convert the following decimals into fractions and reduce them to the lowest form.

(i) 2.125

(ii) 0.0005

(i) 2.125

= 2 + ( 125÷125 / 1000÷125 ) / 125

= 2 +   1 / 8 = 17 / 8

ii) 0.0005

= 5÷5 / 10000÷5

= 1 / 2000

13. Represent the decimal numbers 0.07 and 0.7 on a number line.

The number line of 0.07 and 0.7.

14. Write the following decimal numbers in words.

(i) 4.9 = Four and nine tenths.

(ii) 220.0 = Two hundred and twenty.

(iii) 0.7 = Seven tenths.

(iv) 86.3 = Eighty six and three tenths.

15. Between which two whole numbers the given numbers lie?

(i) 0.2

0 and 1

(ii) 3.4

3 and 4

(iii) 3.9

3 and 4

(iv) 2.7

2 and 3

(v) 1.7

l and 2

(vi) 1.3

1 and 2

16. By how much is 9 /10 km less than 1 km. Express the same in decimal form.

1 – 9/10 km

10–9  / 10 = 1/10 = 0.1 km

Exercise 1.5

1.

2. (i) 305.792 (ii) 1432.67

3. (i) 0.888 (ii) 23.915

4. C is the winner (15.6 s)

5. (i) 117/5 (ii) 46301/1000

6. (i) 0.256 km (ii) 4.567 km

7. Boys = 0.52; Girls=0.48

Challenge problems

8. (i) ₹809.99 (ii) ₹147.70

9. (i) 13.28 m (ii) 4.19 m

10.(i) 8.30 m (ii) 24.200 km

11. (i) 0.0023 (ii) 4.21 (iii) 3.7

12. (i) 17/8 (ii) 1/2000

13.

14. (i) four and nine tenths (ii) Two hundred and twenty  (iii) seven tenths (iv) Eighty six and three tenths

15.(i) 0 and 1 (ii) 3 and 4 (iii) 3 and 4 (iv) 2 and 3  (v) 1 and 2 (vi) 1 and 2

16. 0.1 km

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7th Maths : Term 2 Unit 1 : Number System : Exercise 1.5 | Questions with Answers, Solution | Number System | Term 2 Chapter 1 | 7th Maths