The length of a rectangle is increased by 10% and breadth

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RRB ASM Exam (Ajmer) 2007 click here to view all questions

The length of a rectangle is increased by 10% and breadth decreased by 10%. Then the area of the new rectangle is

Aneither decreased nor increased

Bincreased by 1%

Cdecreased by 1%

Ddecreased by 10%

Nithin K ? Nov 20 '2016 at 19:16

Answer is : decreased by 1%

Explanation :

Suppose
Length is 10cm.
Breadth is 20cm.
Then old Area = Length x Breadth = \(10 \times 20\) = 200 ......................(i)

If Length increased by 10% = 11cm
if Breadth decreased by 10% = 18cm
So, new Area = \(11 \times 18 \)= 198 ..............................(ii)

From (i) and (ii)
old area = 200
new area = 198
So new area is decreased by 1%

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The area of circle is increased by 22 cm. its radius is increased by 1 cm. The original radius of the circle is

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RRB TC CC Exam (Chandigarh) 2008 click here to view all questions

The area of circle is increased by 22 cm. its radius is increased by 1 cm. The original radius of the circle is

A6 cm

B3.2 cm

C3 cm

D3.5 cm

Nithin K ? Apr 7 '2018 at 16:39

Answer is : c.) 3 cm

Explanation:

Let original radius be r.

Then, according to the question,
\(\Large \pi (r+1)^{2}-\pi r^{2} =22\)

\(\implies \Large \pi\times [(r+1)^{2}-r^{2}] =22\)

\(\implies \Large \frac{22}{7}\times (r+1+r)(r+1-r) =22\)

\(\implies 2r+1=7 \implies 2r=6\)

\(r= \Large \frac{6}{2} =\text{3 cm}\)

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The perimeter of the floor of a room is 18 metres.

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RRB TC CC Exam (Chandigarh) 2008 click here to view all questions

The perimeter of the floor of a room is 18 metres. What is the area of the walls of the room. If the height of the room is 3 metres?

A$$21 m^2$$

B$$42 m^2$$

C$$54 m^2$$

D$$108 m^2$$

Nithin K ? Apr 7 '2018 at 16:11

Answer is : c.) \(54\text{ m}^2\)

Explanation:

If the floor is in rectangular shape

Then your answer is, 

Perimeter of rectangle =2(l+b) 

18=2(l+b) 

Then, 

\(\text{Area of four walls =}2(l+b)\times h\)

\(\text{Area of four walls=}18\times3 \)
\(\text{Area of four walls = }54\text{ m²}\)

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There is a rectangular tank of length 180 m and breadth 120

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RRB TA Exam (Chennai) 2008 click here to view all questions

There is a rectangular tank of length 180 m and breadth 120 m in a circular field. If the area of the land portion of the field is 40000 m^2, what is the radius of the field? (take Π = 22/7 )

A130 m

B135 m

C140 m

D145 m

test@gmail ? Oct 17 '2017 at 19:42

Answer is : Option C

Explanation :

Total area of the field  =\( [(180 x 120) + 40000] \text{ }m^2\)

= \((21600 + 40000) \text{ }m^2 = 61600 \text{ }m^2\)

\(\therefore \pi R^2 = 61600\)

⇔ \(R^2\) =\(\Big(61600×\frac{7}{22}\Big)\) = 400 x 7 x 7) m

 R = 20 x 7 =  140 m.

 

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The percentage increase in the area of a rectangle, if each

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RRB TA Exam (Chennai) 2008 click here to view all questions

The percentage increase in the area of a rectangle, if each of its sides is increased by 20% is

A40%

B42%

C44%

D46%

Nithin K ? Dec 4 '2016 at 14:38

Answer :  44%

Explanation:

Let original length = x metres and original breadth = y metres.
Original area = \(\text{xy }m^2\)

Increased length  \(= \frac{120}{100}x\)  and Increased breadth \(= \frac{120}{100}y\)

New area \(=\frac{120}{100}x \times \frac{120}{100}y\)

\(= \frac{36}{25}\text{xy } m^2\)

The difference between the Original area  and New area  is:

\(=\frac{36}{25}xy -xy\)  

\(=\frac{11}{25} xy\)

Increase %  \(= \frac{\frac{11}{25}xy}{xy} \times 100\)  

= 44%

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