Explanation

Ratio boys : girls = 9 : 11
Total students = 80

Total parts = 9 + 11 = 20

Each part = 80 ÷ 20 = 4

Girls = 11 parts:

$$11\times 4=44$$

$$Last\; updated\; question\; NS\; on\; 10\; MAY\; 2026$$

Explanation

• Actual weight = 900 g
• Charged weight = 1000 g

Profit = 100 g (extra charged)

Profit %=100/900​×100=11.11%

Last updated question by NA on 07 May 2026

Explanation

Step-by-step solution:

• 10% of 20 =$frac{10}{100} times 20 = 2$
• 20% of 10 = 20/100​×10=2

Now add both: 2+2=4

Last updated question by NA on 07 May 2026

Explanation

Step 1: Translate the statement into an equation

“One-fourth of one-third of two-fifths of a number is 15”

1​/4×1/3​×2​/5×x=15

Step 2: Multiply fractions

1×1×2/4×3×5​=2/60​= 1/30​

So,

1/30​x=15

Step 3: Solve for x

$$x=15\times 30=450$$

So, the number is

$$x = 450$$

Step 4: Find 40% of the number

40% of 450= 40/100​×450
$$=0.4\times 450=180$$

Last updated question by NA on 07 May 2026

Explanation

This is a distance problem using the Pythagorean theorem.

A person moves:

• 80 km North
• 60 km West

These form a right triangle.

Distance from starting point:

d=  √(80^2 + 60^2)

=√(6400 + 3600)

= √(10000) 

= 100 km

Last updated question by NS on 2 MAY 2026

Explanation

Assume originally:

• Bought 100 items for Rs.100
  So, Cost Price (CP) per item = Rs.1

Now buys 10% less:

• 10% less than 100 = 90 items
• Still spends Rs.100

So new CP per item:

CP= 100/90​

Now sells 10% more:

• 10% more than 100 = 110 items

Assume selling rate is Rs.1 per item.

So total Selling Price:

$$SP=110\times 1=110$$

Profit:

$$Profit=SP-CP=110-100=10$$

Profit percentage formula:

$$\text{Profit \%}=$$Profit/ Cost Price ​×100

Substitute values:

10/100​×100=10%

That approach looks tempting, but it ignores that buying fewer changes the cost per item. The correct combined effect is:

Profit %=(110/90​−1)×100

$(110/90-1)\times 100$

$$=left(frac{20}{90}right)times100$$$$=22.22$$

$$Last\; updated\; question\; by\; NS\; on\; 2\; MAY\; 2026$$

Explanation

To find a single equivalent discount, we apply successive discounts step by step.
Assume original price = 100
Step 1: 10% discount
100 → 90
Step 2: 20% discount on 90
90 → 72
Step 3: 40% discount on 72
72 → 43.2
Final price = 43.2
Total discount:
100 − 43.2 = 56.8

****

Last updated by NS on 01 MAY 2026

Explanation

In this series, each number is formed by adding the square of a natural number (1^2, 2^2, 3^2, .....) to the preceding number.

• 15 + 1² = 16
• 16 + 2² = 20
• 20 + 3² = 29 ← should be 29, but given 30
• 29 + 4² = 45
• 45 + 5² = 70

So the correct sequence should be:

15, 16, 20, 29, 45, 70

Therefore, 30 is the incorrect number

****

Last updated by NS on 01 MAY 2026

Explanation

This is a geometric progression (GP) where each term is multiplied by 3:

1, 3, 9, 27, 81, 243, 729, 2187

Formula:

Here:

• a = 1
• r = 3
• n = 8

So:

8th term = 2187

Last updated by NA on 2 MAY 2026

Explanation

50% of 75% of 200:

• 75% of 200 = 150
• 50% of 150 = 75