129
Q:

# If each side of a square is increased by 25%, find the percentage change in its area?

 A) 65.25 B) 56.25 C) 65 D) 56

Explanation:

let each side of the square be a , then area = a x a

As given that The side is increased by 25%, then

New side = $\inline \fn_jvn \small \frac{125a}{100}$ = $\inline \fn_jvn \small \frac{5a}{4}$

New area = $\inline \fn_jvn \small \left ( \frac{5a}{4} \right )^{2}$

increased area= $\inline \fn_jvn \small \frac{25a^{2}}{16}-a^{2}$

Increase %= $\inline \fn_jvn \small \frac{\left [ \frac{9a^{2}}{16} \right ]}{a^{2}}x100$ % = 56.25%

Q:

The edge of three cubes of metal is 3 m, 4 m and 5 m. They are melted and formed into a single cube. Find the edge of the new cube  ?

 A) 15 m B) 4 m C) 6 m D) 9 m

Explanation:

The edge of the new cube is = $\inline \fn_jvn \small 3^{3}+4^{3}+5^{3}$ = $\inline \fn_jvn \small a^{3}$ => a = 6 m.

1 8
Q:

A rectangular lawn of dimensions 80 m x 60 m has two roads each 10 m wide running in the middle of the lawn, one parallel to the length and the other parallel to the breadth. What is the cost of traveling the two roads at Rs.3 per sq m ?

 A) Rs. 3600 B) Rs. 3800 C) Rs. 3900 D) Rs. 3700

Explanation:

Area = (l + b – d) d

= (80 + 60 – 10)10

=> 1300 sq.mts

=> 1300 x 3 = Rs.3900

2 71
Q:

The ratio between the length and breadth of a rectangular field is 5 : 4 if the breadth is 20m less than the length, the perimeter of the field is :

 A) 260m B) 280m C) 360m D) none of these

Explanation:

5 226
Q:

If a 36 cm thread is used to wrap a book, lengthwise twice and breadth wise once, what is the size of the book ?

 A) 288 sq.cm B) 188 sq.cm C) 144 sq.cm D) 244 sq.cm

Explanation:

Length of the thread is 36 cms.
length wise twice breath wise once then totally thrice.
so 36/3 = 12.
so length is 12 x 2 = 24 cms
breath is 12 cms
Area of the book = length x breath = 24 x 12 = 288 sq.cm

2 150
Q:

If 4 circles of equal radius are drawn with vertices of a square as the centre , the side of the square being 7 cm, find the area of the circles outside the square ?

 A) 119.21 sq cm B) 115.395 sq cm C) 104.214 sq cm D) 111.241 sq cm

Thus total area outside the square is $\inline \fn_jvn \small 4\left ( \frac{3}{4}x\prod x3.5x3.5 \right )$ = 115.3955 sq cm.