21
Q:

# The size of the wooden block is 5 x 10 x 20 cm .How many such blocks will be required to construct a solid wooden cube of minimum size?

 A) 6 B) 8 C) 12 D) 16

Explanation:

Side of smallest cube = L.C.M of 5,10,20 = 20cm

Volume of the cube = (20x20x20)$\inline&space;\fn_jvn&space;cm^3$  = 8000$\inline&space;\fn_jvn&space;cm^3$

Volume of the block= (5x10x20)$\inline&space;\fn_jvn&space;cm^3$ = 1000$\inline&space;\fn_jvn&space;cm^3$

Number of blocks = (8000/1000) = 8

Q:

The circumferences of two circles are 264 meters and 352 meters. Find the difference between the areas of the larger and the smaller circles  ?

 A) 2413 sq.m B) 1234 sq.m C) 4312 sq.m D) 2143 sq.m

Explanation:

Let the radii of the smaller and the larger circles be 's' m and 'l' m respectively.

2∏s = 264 and 2∏l = 352

s = 264/2∏ and l = 352/2∏

Difference between the areas = ∏$\fn_jvn l^{2}$ - ∏$\fn_jvn s^{2}$

= ∏{1762/∏∏ - 1322/∏∏}

= 1762/∏ - 1322/∏

= (176 - 132)(176 + 132)/∏

= (44)(308)/(22/7) = (2)(308)(7) = 4312 sq m

2 231
Q:

If a solid sphere of radius 10 cms is moulded into 8 spherical solid balls of equal radius, then surface area of each ball (in sq.cm) is ?

 A) 100 π B) 101/π C) 99 π/12 D) 54/13π

Explanation:

4/3 π x 10 x 10 x 10 = 8 x 4/3 π rxrxr
r = 5
4π x 5 x 5 = 100π

0 330
Q:

Calculate the number of bricks, each measuring 25 cm x 15 cm x 8 cm required to construct a wall of dimensions 10 m x 4 m x 5 m when 10% of its volume is occupied by concrete ?

 A) 6000 B) 5400 C) 3800 D) 4700

Explanation:

Let 'B' be the nuber of bricks.

=> 10 x 4/100 x 5 x 90/100 = 25/100 x 15/100 x 8/100 x B

=> 10 x 20 x 90 = 15 x 2 x B

=> B = 6000

1 206
Q:

A cuboid of dimension 24cm x 9cm x 8 cm is melted and smaller cubers are of side 3 cm is formed.find how many such cubes can be formed ?

 A) 64 B) 56 C) 48 D) 40

Explanation:

Volume of cuboid = (24 x 9 x 8) cm = 1728 cu.cm
Volume of small cube = (3 x 3 x 3) cm = 27 cu.cm
So,
No. of small cubes formed = 1728/27 = 64.

2 246
Q:

A rectangular block has the dimensions 5x6x7 cm it is dropped into a cylindrical vessel of radius 6cm and height 10 cm. If the level of the fluid in the cylinder rises by 4 cm, What portion of the block is immersed in the fluid ?

 A) 22/7 x 24/35 B) 22/7 x 36 x 4 C) 22/7 x 36/5 D) 22/7 x 37/21

Explanation:

Since level of water increased in cylinder by height 4.
This is because of the rectangular block .

Therefore , area of rectangular block immersed in water is = 22/7 x (6)^2 x 4

Thats why portion of block immersed in water is= (22/7 x 36 x 4) / total vol. of rectangle
= (22/7 x 36 x 4)/(7x5x6)
= 22/7 x 24/35.