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1. The ratio between the length and the breadth of a rectangular park is 3 : 2. If a man cycling along the boundary of the park at the speed of 12 km/hr completes one round in 8 minutes, then the area of the park (in sq. m) is:

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Solution:
Perimeter = Distance covered in 8 min.
Perimeter = (1200060×8)m
Perimeter = 1600 m
Let length = 3x metres and breadth = 2x metres.
Then, 2(3x + 2x) = 1600 or x = 160
Therefore Length = 480 m and Breadth = 320 m
Therefore Area = (480 x 320) m2 = 153600 m2
2. An error 2% in excess is made while measuring the side of a square. The percentage of error in the calculated area of the square is:

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Solution:
100 cm is read as 102 cm.
∴ A1 = (100 x 100) cm2 and A2 (102 x 102) cm2
(A2 - A1) = [(102)2 - (100)2]
              = (102 + 100) x (102 - 100)
              = 404 cm2
∴ Percentage error
=(404100×100×100)%=4.04%
3. The ratio between the perimeter and the breadth of a rectangle is 5 : 1. If the area of the rectangle is 216 sq. cm, what is the length of the rectangle?

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Solution:
2(l+b)b=512l+2b=5b3b=2lb=23lThen,Area = 216cm2l×b=216l×23l=216l2=324l=18cm
4. The percentage increase in the area of a rectangle, if each of its sides is increased by 20% is:

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Solution:
Let original length = x metres and original breadth = y metres
Originalare=(xy)m2Newlength=(120100x)m=(65x)mNewbreadth=(120100y)m=(65y)mNewarea=(65x×65y)m2=(3625xy)m2Thedifferencebetweentheoriginalarea = xyandnewarea3625xyis=(3625)xyxy=xy(36251)=xy(1125)or(1125)xyIncrease%=(1125xy×1xy×100)%=44%
5. A rectangular park 60 m long and 40 m wide has two concrete crossroads running in the middle of the park and rest of the park has been used as a lawn. If the area of the lawn is 2109 sq. m, then what is the width of the road?

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Solution:
Area of the park = (60 x 40) m2 = 2400 m2
Area of the lawn = 2109 m2
∴ Area of the crossroads = (2400 - 2109) m2 = 291 m2
Let the width of the road be x metres. Then,
60x + 40x - x2 = 291
x2 - 100x + 291 = 0
⇒ (x - 97)(x - 3) = 0
x = 3 m
6. The diagonal of the floor of a rectangular closet is 712 feet. The shorter side of the closet is 412 feet. What is the area of the closet in square feet?

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Solution:
OuterSide=(152)2(92)2ft=2254814ft=1444ft=6ftAreaofcloset=(6×4.5)sq.ft=27sq.ft.
7. A towel, when bleached, was found to have lost 20% of its length and 10% of its breadth. The percentage of decrease in area is:

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Solution:
Letoriginallength=xandoriginalbreadth=yDecreaseinarea=xy(80100x×90100y)=xy1825xy=725xyDecrease%=(725xy×1xy×100)%=28%
8. A man walked diagonally across a square lot. Approximately, what was the percent saved by not walking along the edges?

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Solution:
Let the side of the square(ABCD) be x metres.
Then, AB + BC = 2x metres
Area mcq solution image
AC =2 x = (1.41x) m
Saving on 2x metres = (0.59x) m
Saving%=(0.59x2x×100)%=30%(approx)
9. The diagonal of a rectangle is 41 cm and its area is 20 sq. cm. The perimeter of the rectangle must be:

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Solution:
l2+b2=41Also,lb=20(l+b)2=(l2+b2)+2/b=41+40=81(l+b)=9Perimeter=2(l+b)=18cm
10. What is the least number of squares tiles required to pave the floor of a room 15 m 17 cm long and 9 m 2 cm broad?

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Solution:
Lengthoflargesttile=H.C.F.of1517cmand902cm=41cmAreaofeachtile=(41×41)cm2Requirednumberoftiles=1517×90241×41=814