Introduction to Linear Polynomials | Exercise 2.3

Question 4

Suppose the length of a rectangular box is 7 cm and breadth is 11 cm. Find the volume if the height is (i) 5 cm, (ii) 9 cm, (iii) 13 cm. Find the linear pattern representing the volume of the rectangular box.

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Solution

We will use the formula for the volume of a rectangular box.

Step 1 — Find the base area

Let's first find the base area. The length of the box is 7 cm. The breadth of the box is 11 cm. The formula for base area is length times breadth.

Base Area=Length×Breadth\text{Base Area} = \text{Length} \times \text{Breadth}

=7×11= 7 \times 11

77 cm2\boxed{77 \text{ cm}^2}

Diagram 1

Step 2 — Calculate volumes for different heights

Now we can find the volume for each given height. The volume formula is base area times height.

(i) Height is 5 cm.

Volume=77×5\text{Volume} = 77 \times 5

385 cm3\boxed{385 \text{ cm}^3}

(ii) Height is 9 cm.

Volume=77×9\text{Volume} = 77 \times 9

693 cm3\boxed{693 \text{ cm}^3}

(iii) Height is 13 cm.

Volume=77×13\text{Volume} = 77 \times 13

1001 cm3\boxed{1001 \text{ cm}^3}

Diagram 2

Step 3 — Determine the linear pattern

Let's find a general pattern for the volume. Let the height of the box be hh cm. We know the base area is 77 cm². The volume VV is base area multiplied by height.

V=77×hV = 77 \times h

V=77h\boxed{V = 77h}

Answer

(i) The volume is 385 cm³. (ii) The volume is 693 cm³. (iii) The volume is 1001 cm³. The linear pattern is V = 77h.

More questions in Exercise 2.3

Q1

Solve the following:

  1. A student has ₹500 in her savings bank account. She gets ₹150 every month as pocket money. How much money will she have at the end of every month from the second month onwards? Find a linear expression to represent the amount she will have in the nthn^{\text{th}} month.
Q2

A rally starts with 120 members. Each hour, 9 members drop out of the group. How many members will remain after 1, 2, 3, ... hours? Find a linear expression to represent the number of members at the end of the nthn^{\text{th}} hour.

Q3

Suppose the length of a rectangle is 13 cm. Find the area if the breadth is (i) 12 cm, (ii) 10 cm, (iii) 8 cm. Find the linear pattern representing the area of the rectangle.

Q4

Suppose the length of a rectangular box is 7 cm and breadth is 11 cm. Find the volume if the height is (i) 5 cm, (ii) 9 cm, (iii) 13 cm. Find the linear pattern representing the volume of the rectangular box.

Q5

Sarita is reading a book of 500 pages. She reads 20 pages every day. How many pages will be left after 15 days? Express this as a linear pattern.

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