Explanation

Initially, the milkman has 10 liters of milk and adds 10 liters of water, making the total solution 20 liters (10 milk + 10 water).

The ratio of milk to water is 1:1, so the concentration of milk is 50% (10 liters milk / 20 liters total).

The son takes 15 liters of this solution, which contains 50% milk, so he takes 7.5 liters of milk (15 liters x 0.5) and 7.5 liters of water.

The son then adds 5 liters of water to the 15 liters he took, making the total solution 20 liters again (7.5 milk + 7.5 water + 5 water).

Now, the total water in the solution is 7.5 liters (initial water) + 5 liters (added water) = 12.5 liters.

So, the amount of water in the milk is 12.5 liters.

Explanation

To simplify the expression, follow the order of operations:

(-20) + (-8) ÷ (-2) x 3

Divide -8 by -2: -8 ÷ (-2) = 4

Multiply 4 by 3: 4 x 3 = 12

Add -20 and 12: (-20) + 12 = -8

The correct answer is: -8

Explanation

To find the time it takes to travel 120 km:

Speed = Distance / Time = 200 km / 1 hour = 200 km/h

Time to travel 120 km = Distance / Speed

= 120 km / 200 km/h

= 0.6 hours

Convert hours to minutes:

0.6 hours * 60 minutes/hour = 36 minutes

The correct answer is: 36 minutes

Explanation

To calculate the interest:

Principal (P) = Rs. 40,000

Rate (R) = 3% per annum

Time (T) = 4 years

Interest (I) = (P * R * T) / 100

= (40,000 * 3 * 4) / 100

= 4800

The correct answer is: Rs. 4800

Explanation

To evaluate the expression, follow the order of operations:

Multiply 3 and 3: 3 * 3 = 9

Add 3 and 9: 3 + 9 = 12

Subtract 3 from 12: 12 - 3 = 9

Add 3 to 9: 9 + 3 = 12

The correct answer is: 12

Explanation

x^2 > y^2

This implies that the absolute value of x is greater than the absolute value of y.

Explanation

Since 3 is a solution, plug x = 3 into the equation:

3(3)^2 + (k - 1)(3) + 9 = 0

27 + 3k - 3 + 9 = 0

3k + 33 = 0

3k = -33

k = -11

Explanation

Initial ratio: Boys:Girls = 8:5

After 22 more girls join:

Boys = 8x, Girls = 5x + 22 (where x is a constant)

Total students = 286 + 22 = 308

8x + 5x + 22 = 308

13x = 286

x = 22

Boys = 8x = 176

Girls = 5x + 22 = 132

New ratio = Boys:Girls = 176:132 = 4:3 (after simplification)

Explanation

Total heads = 200

Total legs = 580

Calculation:

Let, number of pigeons be x and number of rabbits be y

According to the question,

x + y = 200     ...i)

2x + 4y = 580

⇒ x + 2y = 290     ...ii)

From (i) and (ii) we get,

y = 90

⇒ x = 200 – 90 = 110

∴ There are 110 pigeons in the zoo

Explanation

To evaluate √6048: 6048 = 78 × 78

Therefore, √6048 = 78

So, the correct answer is: 78