Explanation

To find 20% of 50% of 80:

First, find 50% of 80:

50% of 80 = (50/100) * 80 = 0.5 * 80 = 40

Then, find 20% of 40:

20% of 40 = (20/100) * 40 = 0.2 * 40 = 8

So, 20% of 50% of 80 is 8.

 Last updated on 12 NOV 2026

Explanation

A's rate = 1/20 job/min

B's rate = 1/30 job/min

Together rate = 1/20 + 1/30

= (3+2)/60

= 1/12 job/min

Time = 1 / (1/12) = 12 minutes

 Last updated on 12 NOV 2026

Explanation

1. Current Ages:

   • Let Zoya’s current age be $x$
   • Then, Zaid’s current age is $6x$ (since he is six times as old as Zoya).

2. The sum of Ages in 7 Years:

   • In 7 years, Zoya's age will be $x + 7$ and Zaid's age will be $6x + 7$.
   • The sum of their ages in 7 years will be $(x+7)+(6x+7)=49$.

Step 1: Formulate the Equation

x+7+6x+7=49
$$7x+14=49$$

Step 2: Solve for $x$

Subtract 14 from both sides:

$$7x=35$$

Now divide by 7:

$$x=5$$

So, Zoya’s current age is $5$ years and Zaid’s current age is:

$$6x=6\times 5=30$$

Step 3: Determine Zaid’s Age When Zoya Was Born

When Zoya was born, Zaid would have been:

$$30-5=25$$

$$Last\; updated\; on\; 12\; NOV\; 2026$$

Explanation

In the Tree of Rumour problem, one person passes the rumour to 2 other people every 5 minutes.

Therefore, the total number of people triples every 5 minutes.

0 minutes → 1 person

5 minutes → 3 persons

10 minutes → 9 persons

15 minutes → 27 persons

20 minutes → 81 persons

Using the formula:

3^20/5 =3^4 =81

 Last updated on 12 NOV 2026

Explanation

Every year population increase = 700

after five year population increase = 5 x 700= 3500

So intial population = 25000-3500=21500

 Last updated on 12 NOV 2026