BODMAS Rule:

Given:

c is the third proportional of 15 and b.

b is the sum of first three odd natural numbers.

Formula Used:

Third Proportional, c = b²/a

Calculation:

b is the sum of first three odd natural numbers.

⇒ b = 1 + 3 + 5

⇒ b = 9

Third Proportional, c = b²/a

⇒ c = 9²/15

⇒ c = 27/5

∴ Option 3 is the correct answer.

Calculation:

At time = 1 year, the compound interest and simple interest are equal.

Let the principal be 100a

Let the rate be 10% 

Then for 1 year, CI = P[(1 + R/100)¹ - 1]

100a[(1 + 10/100) - 1]

100a[(1 + 1/10) - 1]

100a(1/10) = 10a      ......(1)

Now, for 1 year, SI = PRT/100

(100a × 10 × 1)/100 = 10a      ......(2)

From eq (1) and (2), we can say that at time = 1 year, CI and SI are equal.

Hence, the correct answer is 1 year.

The highest earning was on Thursday.

Additional Information

Earning Day- wise

Sunday = Rs. 100 

Monday = Rs. 500 

Tuesday = Rs. 300 

Wednesday = Rs. 600 

Thursday = Rs. 650 

Friday = Rs. 300 

Saturday =  Rs. 350 

∴ The highest earning was on Thursday.

Given:

Dimensions of cuboid = 5 cm × 7 cm × 11 cm 

Formula used:

Total surface area of cuboid = 2(lb + bh + hl)

Calculation:

Total surface area of cuboid = 2(5 × 7 + 7 × 11 + 11 × 5)

⇒ 2(35 + 77 + 55)

⇒ 2 × 167

⇒ 334 cm²

∴ The required result is 334 cm².

Given:

Principal = Rs. 1000

Time = 2 years

Rate of interest = 2%

Formula:

C.I = P × [(1 + r/100)n – 1]

Here,

P = Principal Amount

r = Rate of interest

n = Time in years

Calculation:

We know that -

C.I = P × [(1 + r/100)n – 1]

According to the question,

C.I = 1000 × [(1 + 2/100)² – 1]

⇒ C.I = 1000 × [(1 + 1/50)² – 1]

⇒ C.I = 1000 × [(51/50)² – 1]

⇒ C.I = 1000 × 101/50 × 1/50

⇒ C.I = 40.4

∴ The Interest Amount will be Rs. 40.4.

Given:

CP = 3450

Repair Price = 450

SP = 5070

Formula used:

Profit% = Profit/CP × 100

Calculation:

The total cost of old phone = 3450 + 450 = 3900

Profit = 5070 - 3900 = 1170

Profit% = 1170/3900 × 100 = 30%

The answer is 30%.

Given:

2 varieties of coffee costing Rs. 330 and Rs. 440 per kg be mixed to get a mixture worth Rs. 363 per kg

Calculation:

Since the price of 2 varieties is Rs. 330 per kg and Rs. 440 per kg,

Mixture Price = Rs. 363

Required ratio should be

= 440 – 363 : 363 – 330

= 77 : 33

= 7 : 3

Given:

Food Bill = Rs. 4,750, D₁ = 40%, and D₂ = 10%

Calculation:

Amount paid = 4750 × (100 - 40)% × (100 - 10)%

⇒ 4750 × 60% × 90%

⇒ 4750 × 0.6 × 0.9 = 2565

∴ The amount paid by Imran is Rs. 2565

Given:

The ratio of the efficiencies of A, B and C = 5 : 3 : 2

Time taken by them to complete the task = 21 hours

Concept used:

Work = Efficiency × Time

Calculation:

Total 1 hour work = 5d + 3d + 2d = 10d

Work completed in 21 hours = (21 × 10d) = 210 d