Question

a cube of 5 cm is surmounted by another cube 2 cm is painted aat the rate rs 1 per cm 2 .then find the cost of painting the toy.​

Answer 1

Answer:

Let First cube be A = 5cm

Therefore, area of cube = 4A² = (4×5×5)cm²

= 100cm²

Let second cube be a = 2cm = 4a² = (4×2×2) cm²

=16cm²

Therefore, Area of the toy = 100cm² + 16cm² = 116cm²

Cost of painting/ per cm² = ₹1

116 cm² = 116cm² × ₹1 = ₹116

Hence, cost of painting the toy is ₹116.

Answer 2

Given data : A cube of 5 cm is surmounted by another cube 2 cm is painted at the rate Rs 1 per cm².

To find : find the cost of painting the toy.

Solution : Here, a/c to question there are two cubes.

Let the side of the larger cube be 5 cm and that of the smaller cube is 2 cm.

Now,

➜ Area of larger cube = 6a²

Where, a is side

➜ Area of larger cube = 6 * 5²

➜ Area of larger cube = 6 * 25

➜ Area of larger cube = 150 cm²

and

➜ Area of smaller cube = 6a²

Where, a is side

➜ Area of smaller cube = 6 * 2²

➜ Area of smaller cube = 6 * 4

➜ Area of smaller cube = 24 cm²

Now,

➜ Total surface area of both cube = Area of larger cube + Area of smaller cube

➜ Total surface area (of both cube) = 150 + 24

➜ Total surface area (of both cube) = 174 cm²

Here, we know that, due to surmounting one face of smaller cube and some part of face of larger cube escape from painting.

Hence,

➜ Remaining area = 2 * (side of smaller cube)²

➜ Remaining area = 2 * 2²

➜ Remaining area = 2 * 4

➜ Remaining area = 8 cm²

Now,

➜ Area to be painted = Total surface area - Remaining area

➜ Area to be painted = 174 - 8

➜ Area to be painted = 166 cm²

Now,

➜ Cost painting = Area to be painted * Rate of painting

➜ Cost painting = 166 * 1

➜ Cost painting = Rs 166

Answer : Hence, cost of painting is Rs 166.