Mathematics Mcqs

A typist uses a paper 30cm x 15cm.He leaves a margin at 2.5cm at the top and the bottom and 12.5cm on either side. What percentage of paper area is approximately available for typing

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A typist uses a paper 30cm x 15cm.He leaves a margin at 2.5cm at the top and the bottom and 12.5cm on either side. What percentage of paper area is approximately available for tyg

A. 65%
B. 70%
C. 80%
D. 60%

Explanation:
Total area =(30 x 15)Sq.cm =45 Sq.cm
Area used =[(30 – 1.25 x 2) x (15 -2.5 x2)]
=(27.5 x 10)Sq.cm =275 Sq.cm
Percentage of area used =(275/450 x 100)% =61.1%
= 60%(Approx.)

The areas of two similar triangles are 12 cm2 and 48SQ. cm .If the height of the smaller one is 2.1cm than the corresponding height of the bigger one is_________?

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The areas of two similar triangles are 12 cm2 and 48SQ. cm .If the height of the smaller one is 2.1cm than the corresponding height of the bigger one is_________?

A. 0.525cm
B. 4.2cm
C. 80%
D. 60%

Explanation:
The area of two similar triangles is the ratio of the square of the corresponding heights.
Therefore , 12/48 = (2.1)2 /h2
=> h2 = 4 x (2.1)2
=> h=(2 x 2.1)=4.2 cm

If the height of a triangle is decreased by 40% and its base is increased by 40% what will be the effect on its area?

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If the height of a triangle is decreased by 40% and its base is increased by 40% what will be the effect on its area?

A. No change
B. 8%decrease
C. 16% Decrease
D. 16%increases

Explanation:
let the height be ‘h’ and base = b, then area =(1/2 bh)sq.units
New height =(60 % of h) = (60/100 h) = 3h/5
New base =(140% of b) =(140/100 b) =(76/5)
New area =(1/2 x 7b/5 x 3h/5) Sq.units =(21/50 bh)sq.units
Decrease in area =(1/2bh – 21/50bh)= 4/50 bh
Decrease % =(4/50bh. 2/bh x 100)% =16%

The sides of a triangle are in the ratio ½: 1/3: ¼. If the perimeter is 52cm then the length of the smallest side is________?

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The sides of a triangle are in the ratio ½: 1/3: ¼. If the perimeter is 52cm then the length of the smallest side is________?

A. 9cm
B. 10cm
C. 11cm
D. 12cm
Explanation:
Ratio of sides = ½ : 1/3 : ¼ = 6: 4 : 3
Side are (32 x 6/13)cm, (32 x 4/13)cm and (52 x 3/13)cm i.e…, 24 cm , 16 cm, 12 cm.
Length of smallest side = 12 cm