Question

Check your guess
(a) Measure the yellow rectangle. It is ________ cm long.
(b) How many stamps can be placed along its length? ________
(c) How wide is the rectangle? ________ cm
(d) How many stamps can be placed along its width? ________
(e) How many stamps are needed to cover the rectangle? ________
(f) How close was your earlier guess? Discuss.
(g) What is the area of the rectangle? ________ square cm
(h) What is the perimeter of the rectangle? ________ cm

Answer 1

(a) The yellow rectangle is 14 cm long.

(b) Measure the length of stamp already placed on it with the help of a ruler.
Length of stamp = 2 cm.
So, the required number of stamps = $\frac{\mathrm{Length}\mathrm{of}\mathrm{rectangle}}{\mathrm{Length}\mathrm{of}\mathrm{stamp}}$
= $\frac{14}{2}$
= 7

Thus, we can place 7 stamps along the length of the rectangle.

(c) The breadth of yellow rectangle is 8 cm.

(d) Measure the width of stamp placed along its width with the help of a ruler.
Width of stamp = 2 cm
So, the required number of stamps = $\frac{\mathrm{Breadth}\mathrm{of}\mathrm{rectangle}}{\mathrm{Breadth}\mathrm{of}\mathrm{stamp}}$
= $\frac{8}{2}$
= 4

Thus, we can place 4 stamps along the breadth of the rectangle.

(e) The number of stamps that can be placed in the rectangle = 7 $\times$ 4
= 28

(f) Our guess for the stamp was 27, but the actual answer is 28. So, we can say that our guess was quite close to the correct answer.

(g) Area of rectangle = 7 cm $\times$ 4 cm
= 28 square cm

The area of rectangle is 28 square cm.

(h) Length of the rectangle = 14 cm
Breadth of the rectangle = 8 cm

A rectangle has 2 lengths and 2 breadths.

So, perimeter of the rectangle = Sum of all its sides
= Length of its boundary
= 14 cm + 8 cm + 14 cm + 8 cm
= 44 cm

The perimeter of rectangle is 44 cm.