Follow BODMAS rule to solve this question, as per the order given below,

Step-1- Parts of an equation enclosed in 'Brackets' must be solved first, and in the bracket,

Step-2- Any mathematical 'Of' or 'Exponent' must be solved next,

Step-3- Next, the parts of the equation that contain 'Division' and 'Multiplication' are calculated,

Step-4- Last but not least, the parts of the equation that contain 'Addition' and 'Subtraction' should be calculated.

Given expression is,

⇒ (8.88 × 5.25) + 54.80 = ? × 4.19 + 27.897

We can write the given values as:

⇒ 8.88 ≈ 9 and 5.25 ≈ 5 and 54.80 ≈ 55

⇒ 4.19 ≈ 4 and 27.897 ≈ 28

Then,

⇒ (9 × 5) + 55 = ? × 4 + 28

⇒ 45 + 55 = ? × 4 + 28

⇒ 100 = ? × 4 + 28

⇒ 100 - 28 = ? × 4

⇒ 72 = ? × 4

⇒ ? = 72/4

∴ ? ≈ 18

Follow BODMAS rule to solve this question, as per the order given below,

Step-1- Parts of an equation enclosed in 'Brackets' must be solved first, and in the bracket,

Step-2- Any mathematical 'Of' or 'Exponent' must be solved next,

Step-3- Next, the parts of the equation that contain 'Division' and 'Multiplication' are calculated,

Step-4- Last but not least, the parts of the equation that contain 'Addition' and 'Subtraction' should be calculated.

Given expression is,

⇒ 115.72 ÷ 4.10 × 4.90 = 90.14% of 200 - ?

We can write the given values as :

⇒ 115.72 ≈ 116 and 4.10 ≈ 4

⇒ 4.90 ≈ 5 and 90.14 ≈ 90

Then,

⇒ 116 ÷ 4 × 5 = 90% of 200 - ?

⇒ 116 ÷ 4 × 5 = (90/100) × 200 - ?

⇒ 29 × 5 = 90 × 2 - ?

⇒ 145 = 180 - ?

⇒ ? = 180 - 145

∴ ? ≈ 35

The pattern of the given series is:

⇒ 15 + 1³ = 15 + 1 = 16

⇒ 16 - 2² = 16 - 4 = 12

⇒ 12 + 3³ = 12 + 27 = 39

⇒ 39 - 4² = 39 - 16 = 23

⇒ 23 + 5³ = 23 + 125 = 148 = ?

The pattern of the given series is:

⇒ 2 + 1² + 1 = 2 + 1 + 1 = 4

⇒ 4 + 2² + 2 = 4 + 4 + 2 = 10

⇒ 10 + 3² + 3 = 10 + 9 + 3 = 22

⇒ 22 + 4² + 4 = 22 + 16 + 4 = 42 = ?

The pattern of the given series is:

⇒ 4 × 0.5 + 0.5 = 2 + 0.5 = 2.5

⇒ 2.5 × 1 + 1 = 2.5 + 1 = 3.5

⇒ 3.5 × 1.5 + 1.5 = 5.25 + 1.5 = 6.75

⇒ 6.75 × 2 + 2 = 13.5 + 2 = 15.5 = ?

The pattern of the given series is:

⇒ 17 + 1² = 17 + 1 = 18

⇒ 18 - 2² = 18 - 4 = 14

⇒ 14 + 3² = 14 + 9 = 23

⇒ 23 - 4² = 23 - 16 = 7

⇒ 7 + 5² = 7 + 25 = 32 = ?

Let the amount lent at 5% be Rs. x

∴ Money lent at 3% = Rs. (4000 – x)

Simple interest on Rs. x = (Principal × Time × Rate)/100

⇒ Simple interest = (x × 4 × 5)/100 = Rs. x/5

Total interest = Rs. 640

∴ Interest on Rs. (4000 – x) = Rs. (640 – x/5)

⇒ [(4000 – x) × 4 × 3)]/100 = 640 – x/5

⇒ 3(4000 – x)/25 = 640 – x/5

⇒ 12000 – 3x = 16000 – 5x

⇒ 2x = 4000

⇒ x = 2000

∴ Money lent at 5% is Rs. 2000

Let the number of failed candidates = x

Number of passed candidates = 5x

Total number of candidates = 5x + x = 6x

According to the question

(5x - 75 - 10)/(x + 10) = 1/2

⇒ 10x - 150 - 20 = x + 10

⇒ 10x - x = 180

⇒ 9x = 180

⇒ x = 20

∴ Total number of candidates = 20 × 6 = 120

⇒ Length of bridge = 1 km = 1000 m

⇒ Length of train = 1000/2 = 500 m

⇒ Total distance travelled = (1000 + 500) m = 1500 m

⇒ Time taken = 2 min

∴ Speed of train = 1500/2 = 750 m/min

Total price of milk in mixture = 30 × Rs. 40 = Rs. 1200

Total price of water in mixture = N × Rs. 1 = Rs. N

⇒ Average price of mixture = (1200 + N)/(30 + N) = 24.4

⇒ 1200 + N = 732 + 24.4N

⇒ N = 468/23.4 = 20