Mathematics
Assertion (A) : The length, breadth and height of the cuboid are 15 cm, 12 cm and 9 cm respectively. Lateral surface area of the cuboid = 846 cm2.
Reason (R) : Lateral surface area of cuboid = 2 x h x (l + b) square units.
Both A and R are correct, and R is the correct explanation for A.
Both A and R are correct, and R is not the correct explanation for A.
A is true, but R is false.
A is false, but R is true.
Answer
When l, b and h represent the length, breadth, and height, respectively of the cuboid.
By formula,
Lateral surface area = 2(l + b)h
So, reason (R) is true.
Substituting values, we get :
Lateral surface area = 2 x (15 + 12) x 9
= 2 x 27 x 9
= 486 cm2.
So, assertion (A) is false.
∴ A is false, but R is true.
Hence, option 4 is the correct option.
Related Questions
Assertion (A) : The length, breadth and height of an open cuboid are 10 cm, 12 cm and 6 cm respectively. If the thickness is 1 cm, then internal dimensions are 8 cm, 10 cm and 5 cm respectively.
Reason (R) : If l, b and h are the external dimension of an open cuboid of thickness 'x', then its internal dimension are (l - 2x), (b - 2x) and (h - x) respectively.
Both A and R are correct, and R is the correct explanation for A.
Both A and R are correct, and R is not the correct explanation for A.
A is true, but R is false.
A is false, but R is true.
Assertion (A) : Three solid silver cubes of side 6 cm, 8 cm and 10 cm are melted and recasted into a single solid cube. The side of the new cube = 2 times the side of the smallest cube.
Reason (R) : Volume of cuboid = (l x b x h) cubic units.
Both A and R are correct, and R is the correct explanation for A.
Both A and R are correct, and R is not the correct explanation for A.
A is true, but R is false.
A is false, but R is true.
A cuboid is 8 m long, 12 m broad and 3.5 m high. Find its
(i) total surface area
(ii) lateral surface area