# RD Sharma Solutions for Class 8 Math Chapter 4 - Cubes and Cube Roots (Part-5) Notes | Study RD Sharma Solutions for Class 8 Mathematics - Class 8

## Class 8: RD Sharma Solutions for Class 8 Math Chapter 4 - Cubes and Cube Roots (Part-5) Notes | Study RD Sharma Solutions for Class 8 Mathematics - Class 8

The document RD Sharma Solutions for Class 8 Math Chapter 4 - Cubes and Cube Roots (Part-5) Notes | Study RD Sharma Solutions for Class 8 Mathematics - Class 8 is a part of the Class 8 Course RD Sharma Solutions for Class 8 Mathematics.
All you need of Class 8 at this link: Class 8

#### Answer 1: Because 7 lies between 1 and 100, we will look at the row containing 7 in the column of x.By the cube root table, we have:

1.913

Thus, the answer is 1.913.

4.121

#### Answer 3: We have:

700=70×10700=70×10
Cube root of 700 will be in the column of   against 70.

By the cube root table, we have:

=8.879

Thus, the answer is 8.879.

#### Answer 4: We have:

7000=70×1007000=70×100

By the cube root table, we have:

=1.913×10=19.13

#### Answer 5: We have:

1100=11×1001100=11×100

By the cube root table, we have:

=2.224×4.642=10.323 (Up to three decimal places)11003=113×1003=2.224×4.642=10.323 (Up to three decimal places)

Thus, the answer is 10.323.

#### Answer 6: We have:

780=78×10780=78×10

Cube root of 780 would be in the column of  against 78.

By the cube root table, we have:

= 9.205

Thus, the answer is 9.205.

#### Answer 7: We have:

7800=78×1007800=78×100

By the cube root table, we have:

=4.273×4.642=19.835 (upto three decimal places)

Thus, the answer is 19.835

#### Answer 8: By prime factorisation, we have:

1346=2×673

Also

670<673<680

From the cube root table, we have:

For the difference (680-670), i.e., 10, the difference in the values

=8.7948.750=0.044=8.794-8.750=0.044

For the difference of (673-670), i.e., 3, the difference in the values

×3=0.0132=0.013=0.04410×3=0.0132=0.013 (upto three decimal places)

=8.750+0.013=8.7636733=8.750+0.013=8.763

Now

=1.260×8.763=11.04113463=23×6733=1.260×8.763=11.041 (upto three decimal places)

Thus, the answer is 11.041.

#### Answer 9: We have:

250=25×100250=25×100

Cube root of 250 would be in the column of  against 25.

By the cube root table, we have:

Thus, the required cube root is 6.3.

#### Answer 10: By prime factorisation, we have:

5112=23×32×71

By the cube root table, we have:

=2×2.080×4.141=17.22751123=2×93×713=2×2.080×4.141=17.227 (upto three decimal places)

Thus, the required cube root is 17.227.

#### Answer 11: We have:

9800=98×1009800=98×100

By cube root table, we have:

=4.610×4.642=21.4098003=983×1003=4.610×4.642=21.40 (upto three decimal places)

Thus, the required cube root is 21.40.

#### Answer 12: We have:

730<732<740

From cube root table, we have:

For the difference (740-730), i.e., 10, the difference in values

=9.0459.004=0.041=9.045-9.004=0.041

For the difference of (732-730), i.e., 2, the difference in values

2=0.0082

=9.004+0.008=9.012

#### Answer 13: We have:

7300<7342<7400

From the cube root table, we have:

For the difference (7400-7300), i.e., 100, the difference in values

=19.4819.39=0.09

For the difference of (7342-7300), i.e., 42, the difference in the values

×42=0.0378=0.037

=19.39+0.037=19.427

#### Answer 14: We have:

133100=1331×100

By cube root table, we have:

=4.6421003=4.642

=11×4.642=51.062

#### Answer 15: We have:

37800=23×33×175

Also

170<175<180

From cube root table, we have:

For the difference (180-170), i.e., 10, the difference in values

=5.6465.540=0.106=5.646-5.540=0.106

For the difference of (175-170), i.e., 5, the difference in values

×5=0.053=0.10610×5=0.053

=5.540+0.053=5.5931753=5.540+0.053=5.593

Now

37800=6×  =6×5.593=33.55837800=6×1753=6×5.593=33.558

Thus, the required cube root is 33.558.

#### Answer 16: The number 0.27 can be written as 27/100.

Now

By cube root table, we have:

=
0.646
0.273=31003=34.642=0.646
.

Thus, the required cube root is 0.646.

#### Answer 17: The number 8.6 can be written as 86/10.

Now

By cube root table, we have:

2.0498.63=863103=4.4142.154=2.049

Thus, the required cube root is 2.049.

#### Answer 18: The number 0.86 could be written as 86/100.

Now

By cube root table, we have:

=0.9510.863=8631003=4.4144.642=0.951 (upto three decimal places)

Thus, the required cube root is 0.951.

#### Answer 19: The number 8.65 could be written as 865/100.

Now

Also

860<865<870

From the cube root table, we have:

For the difference (870-860), i.e., 10, the difference in values

=9.5469.510=0.036=9.546-9.510=0.036
For the difference of (865-860), i.e., 5, the difference in values
×5=0.018  (upto three decimal places)

9.510+0.018=9.5288653=9.510+0.018=9.528 (upto three decimal places)

From the cube root table, we also have:

2.0538.653=86531003=9.5284.642=2.053 (upto three decimal places)

Thus, the required cube root is 2.053.

#### Answer 20: We have:

7500<7532<7600

From the cube root table, we have:

For the difference (7600-7500), i.e., 100, the difference in values

=19.6619.57=0.09=19.66-19.57=0.09

For the difference of (7532-7500), i.e., 32, the difference in values

×32=0.0288=0.029=0.09100×32=0.0288=0.029 (up to three decimal places)

=19.57+0.029=19.59975323=19.57+0.029=19.599

#### Answer 21: We have:

830<833<840

From the cube root table, we have:

For the difference (840-830), i.e., 10, the difference in values

=9.4359.398=0.037=9.435-9.398=0.037

For the difference (833-830), i.e., 3, the difference in values

×3=0.0111=0.011=0.03710×3=0.0111=0.011 (upto three decimal places)

=9.398+0.011=9.4098333=9.398+0.011=9.409

#### Answer 22: The number 34.2 could be written as 342/10.

Now

Also

340<342<350

From the cube root table, we have:

For the difference (350-340), i.e., 10, the difference in values

=7.0476.980=0.067=7.047-6.980=0.067.

For the difference (342-340), i.e., 2, the difference in values

×2=0.013=0.06710×2=0.013  (upto three decimal places)

=6.980+0.0134=6.9933423=6.980+0.0134=6.993 (upto three decimal places)

From the cube root table, we also have:

3.246

Thus, the required cube root is 3.246.

#### Answer 23: Volume of a cube is given by:

V=a3V=a3, where a = side of the cube

∴∴ Side of a cube = a=

If the volume of a cube is 275 cm3, the side of the cube will be

We have:

270<275<280

From the cube root table, we have:

For the difference (280-270), i.e., 10, the difference in values

=6.5426.463=0.079=6.542-6.463=0.079

For the difference (275-270), i.e., 5, the difference in values

×5=0.0395   0.04=0.07910×5=0.0395  ≃ 0.04 (upto three decimal places)

=6.463+0.04=6.5032753=6.463+0.04=6.503 (upto three decimal places)

Thus, the length of the side of the cube is 6.503 cm.

The document RD Sharma Solutions for Class 8 Math Chapter 4 - Cubes and Cube Roots (Part-5) Notes | Study RD Sharma Solutions for Class 8 Mathematics - Class 8 is a part of the Class 8 Course RD Sharma Solutions for Class 8 Mathematics.
All you need of Class 8 at this link: Class 8
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