NCERT Class 8 Mathematics Solutions: Chapter 11 –Mensuration Exercise 11.3 Part 1

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Surface area and volume of cuboid

Surface Area and Volume of Cuboid

Surface area and volume of cuboid

1. There are two cuboidal boxes as shown in the adjoining figure. Which box requires the lesser amount of material to make?

Two Cuboidal Boxes

Two cuboidal boxes, height 50 cm, width 40 cm, and length 60 cm also second box height 50, width 50 cm, length 50 cm

Answer:

(a) Given,

Length of cuboidal box

Breadth of cuboidal box

Height of cuboidal box

Area surface area of cuboidal box

(b) Given,

Length of cuboidal box

Breadth of cuboidal box

Height of cuboidal box

Area surface area of cuboidal box

So, the cuboidal box requires the lesser amount to make.

Since, surface area of box is less than that of box .

1. Find the values of the letters in the following and give reasons for the steps involved.

Answer:

We observe that

So, that .

Putting at ones place and carry over and ,

we get

So,

2. Find the values of the letters in the following and give reasons for the steps involved.

Answer:

Here on putting ,

we get .

And

Hence,

3. Find the values of the letters in the following and give reasons for the steps involved.

Answer:

Here on putting ,

we get .

And

Hence,

4. Find the values of the letters in the following and give reasons for the steps involved.

Answer:

Here product of must be same as ones place digit as .

On putting , we get the ones digit and remaining two B’s value should be .

For

So,