The correct answer is option 2 i.e. 325.

Let the passing mark be 'P'

Percentage required to pass the exam = 65%

Student got 285 marks and failed by 8%, which means the percentage achieved by the student is 65 - 8 = 57%

If 57% of P = 285

⇒ P = (285 × 100)/57 = 500

So the passing mark is 65% of P 

⇒ (65/100) × 500 = 325

The correct answer is option 2 i.e. 21 : 64.

The ratio of length, breadth, and height of the cuboid is = 7 : 4 : 6

i.e. let Length be = 7x

Breadth be = 4x

Height be = 6x

Volume of Cuboid = length × breadth × height 

⇒ 7x × 4x × 6x = 168x³

Now, the Height of the cuboid is 75% of the edge of the cube

i.e. if the edge of a cube is y,

75/100 × y = 6x

⇒ y = 8x

Hence, volume of cube = (edge)³ = (8x)³ = 512x³

The ratio of volumes of cuboid and cube is: 168x³/512x³ = 21 : 64

The correct answer is option 2 i.e. -0.12.

0.2 × 0.05 of 8 - 0.25 ÷ (0.4 + 0.85)

Using BODMAS

We simplify

⇒ 0.2 × 0.4 - 0.25 ÷ 1.25

⇒ 0.2 × 0.4 - 0.2

⇒ 0.08 - 0.2 = -0.12

The correct answer is Option 2 i.e. 129.6 seconds

The correct answer is Option 2 i.e. 180 days

A's 1-day  work = (1/90)

B's 1-day work = (1/120)

(A + B)'s 1-day work = (1/90) + (1/120) = (7/360)

(A + B)'s 20-day work = (7/360) × 20 = (140/360) = (7/18)

Remaining work = 1 - (7/18) = (11/18)

now let C's 1-day work = (1/p)

⇒(10/120) + (1/120 + 1/p) × 38 = (11/18)

⇒ p = 180

Hence,

In 180 days, C can do it alone.

The correct answer is Option 3 i.e. 64 cm²

The correct answer is Option 2 i.e. 7.

Let the number of heavy blankets in the house be 'x'

Total weight of heavy blankets in the house = 32kg

Total weight of light blankets in the house = 6 × 10/3 = 20 kg

Total weight = (32 + 20) = 52 kg

Total  number of blankets = (6 + x)

⇒ 4 = 52/(6 + x)

⇒ (24 + 4x) = 52

⇒ 4x = 28

⇒ x = 7

The correct answer is Option 3 i.e. 57

Let the smaller number be x

Larger number = x + 1

Sum = 115

x + x + 1 = 115

2x = 114

x = 57

The correct answer is option 3 i.e. 9 days