Question

Length of a rectangle is three times its breadth. Perimeter of the rectangle is 40 cm. Find itslength and width.

1 point

5,15

15,5

20,2.5

2.5,20​

Answer 1

Let the length be = L

and breadth = B

Given L = 3B

Perimeter = 40cm

Perimeter of rectangle = 2(L + B)

40 = 2(3B + B)

40/2 = 4B

20 = 4B

B = 20/4

B = 5cm

L = 3B = 3 × 5

L = 15 cm

15, 5 is the answer

Answer 2

$\mathfrak{ \large{ \pink{ \underline{ \blue{ Correct \: question: }}}}}$

Length of a rectangle is three times its breadth. Perimeter of the rectangle is 40 cm. Find its length and width.

a) 5,15

b) 15,5

c) 20,2.5

d) 2.5,20

$\mathfrak{ \large{ \pink{ \underline{ \blue{ To \: find: }}}}}$

• Length and breadth of rectangle

$\mathfrak{ \large{ \pink{ \underline{ \blue{ Solution: }}}}}$

• Let the breadth of rectangle be x cm
• Let the length of rectangle be 3x cm
• Perimeter of the rectangle = 40 cm

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \mathfrak{ \underline{ \green{Formula\: to\: calculate\: the\: perimeter\: of\: rectangle}}}$

$\boxed{ \rm{{ \red{ perimeter = 2(length + breadth)}}}}$

According to question,

$\large{ \tt : \implies \: \: \: \: \: \: \: \: \: \: 2(x + 3x) = 40}$

$\large{ \tt : \implies \: \: \: \: \: \: \: \: \: \: 2 \times 4x = 40}$

$\large{ \tt : \implies \: \: \: \: \: \: \: \: \: \: 4x = \frac{40}{2} }$

$\large{ \tt : \implies \: \: \: \: \: \: \: \: \: \: 4x = 20}$

$\large{ \tt : \implies \: \: \: \: \: \: \: \: \: \: x = \cancel\frac{20}{4} }$

$\large{ \tt : \implies \: \: \: \: \: \: \: \: \: \: x = 5}$

Now,

• Breadth of rectangle = x = 5 cm
• Length of rectangle = 3x = 15 cm

$\mathfrak{ \large{ \pink{ \underline{ \blue{ Hence:}}}}}$

The length and breadth of rectangle are 15 cm and 5 cm