In the year 2000, Monu was 3 times his sister’s age. In 2010, he was 24 years older than her. Find Monu’s age in 2010.

The correct answer is 46 years.

Let's solve the problem step-by-step to find Monu's age in the year 2010.

Step 1: Understand the relationship between ages over time.
The difference between the ages of two people remains constant throughout their lives. Therefore, if Monu was 24 years older than his sister in 2010, he was also 24 years older than her in 2000.

Step 2: Set up equations for the year 2000.
Let the sister's age in the year 2000 be $x$ years.
According to the problem statement, in 2000, Monu was 3 times his sister's age. So, Monu's age in 2000 was $3x$ years.

The age difference between Monu and his sister in 2000 is given by:

$3x-x=24$

$2x=24$

$x=12$

So, in the year 2000:

Sister's age = 12 years
Monu's age = $3\times 12=36$ years

Step 3: Calculate Monu's age in the year 2010.
The time difference between 2000 and 2010 is 10 years ($2010-2000=10$ years).

Monu's age in 2010 = Monu's age in 2000 + 10 years

$\text{Monu's age in 2010}=36+10=46\text{years}$

Thus, Monu's age in 2010 was 46 years.