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Question

13 years ago, Ram was twice as old as Sunny. Three years from now Sunny’s age will be 3/5 of Ram’s age. What is Ram’s current age?

This question was previously asked in
RRB ALP 2018 CBT 2 Fitter Question Paper (21-Jan-2019) (Shift 3)
The correct answer is

77 years

Solving the Ram and Sunny Age Problem

This question asks us to find Ram's current age based on information about his and Sunny's ages at two different points in time. We can solve this type of problem by setting up algebraic equations.

Defining Variables for Current Ages

Let's represent the current ages of Ram and Sunny using variables:

  • Let \( R \) be Ram's current age in years.
  • Let \( S \) be Sunny's current age in years.

Setting Up Equations from the Given Conditions

We are given two conditions:

  1. 13 years ago, Ram was twice as old as Sunny.
  2. Three years from now, Sunny's age will be 3/5 of Ram's age.

Condition 1: 13 Years Ago

13 years ago:

  • Ram's age was \( R - 13 \)
  • Sunny's age was \( S - 13 \)

The condition states that Ram's age was twice Sunny's age:

\( R - 13 = 2(S - 13) \)

Let's simplify this equation:

\( R - 13 = 2S - 26 \)

\( R = 2S - 26 + 13 \)

\( R = 2S - 13 \quad \text{(Equation 1)} \)

Condition 2: Three Years From Now

Three years from now:

  • Ram's age will be \( R + 3 \)
  • Sunny's age will be \( S + 3 \)

The condition states that Sunny's age will be 3/5 of Ram's age:

\( S + 3 = \frac{3}{5}(R + 3) \)

Let's simplify this equation by multiplying both sides by 5 to clear the fraction:

\( 5(S + 3) = 3(R + 3) \)

\( 5S + 15 = 3R + 9 \)

Rearranging the terms to group \( S \) and \( R \):

\( 5S - 3R = 9 - 15 \)

\( 5S - 3R = -6 \quad \text{(Equation 2)} \)

Solving the System of Equations

Now we have a system of two linear equations with two variables:

  • \( R = 2S - 13 \quad \text{(Equation 1)} \)
  • \( 5S - 3R = -6 \quad \text{(Equation 2)} \)

We can use the substitution method. Substitute the expression for \( R \) from Equation 1 into Equation 2:

\( 5S - 3(2S - 13) = -6 \)

Distribute the -3:

\( 5S - 6S + 39 = -6 \)

Combine the \( S \) terms:

\( -S + 39 = -6 \)

Subtract 39 from both sides:

\( -S = -6 - 39 \)

\( -S = -45 \)

Multiply by -1 to solve for \( S \):

\( S = 45 \)

So, Sunny's current age is 45 years.

Now, substitute the value of \( S \) (45) back into Equation 1 to find \( R \):

\( R = 2S - 13 \)

\( R = 2(45) - 13 \)

\( R = 90 - 13 \)

\( R = 77 \)

So, Ram's current age is 77 years.

Verifying the Solution

Let's check if Ram's current age of 77 and Sunny's current age of 45 satisfy the original conditions:

  • 13 years ago:

    • Ram's age: \( 77 - 13 = 64 \)
    • Sunny's age: \( 45 - 13 = 32 \)

    Is 64 twice 32? \( 2 \times 32 = 64 \). Yes, the first condition is met.

  • 3 years from now:

    • Ram's age: \( 77 + 3 = 80 \)
    • Sunny's age: \( 45 + 3 = 48 \)

    Is 48 equal to 3/5 of 80? \( \frac{3}{5} \times 80 = \frac{3 \times 80}{5} = \frac{240}{5} = 48 \). Yes, the second condition is met.

Both conditions are satisfied, so our calculated current ages for Ram and Sunny are correct.

Ram's current age is 77 years.

The final answer is 77 years.


Age Problem Summary
Person Current Age Age 13 Years Ago Age 3 Years From Now
Ram \( R = 77 \) \( R - 13 = 64 \) \( R + 3 = 80 \)
Sunny \( S = 45 \) \( S - 13 = 32 \) \( S + 3 = 48 \)

Revision Table for Age Problems

Key Steps for Solving Age Problems
Step Description Example Application
Define Variables Assign variables to the current ages of individuals. Let Ram's current age be \( R \), Sunny's current age be \( S \).
Express Ages at Different Times Write expressions for ages in the past or future based on current age and the time difference. Age 13 years ago: \( \text{Current Age} - 13 \). Age 3 years from now: \( \text{Current Age} + 3 \).
Formulate Equations Translate the given relationships between ages into algebraic equations. "Ram was twice as old as Sunny": \( R - 13 = 2(S - 13) \). "Sunny's age will be 3/5 of Ram's age": \( S + 3 = \frac{3}{5}(R + 3) \).
Solve System of Equations Use methods like substitution or elimination to find the values of the variables. Solve \( R = 2S - 13 \) and \( 5S - 3R = -6 \) simultaneously.
Check Solution Substitute the obtained values back into the original problem conditions to ensure they are satisfied. Verify \( 64 = 2 \times 32 \) and \( 48 = \frac{3}{5} \times 80 \).

Additional Information on Age Word Problems and Linear Equations

Age word problems are common types of algebraic problems that involve finding the ages of one or more people based on given information about their ages at different points in time. These problems often require setting up and solving a system of linear equations.

Key Concepts:

  • Variables: Represent unknown quantities (usually current ages) with variables like \( x \) or \( y \), or initial letters like \( R \) and \( S \) for clarity.
  • Expressions for Past/Future Ages: If the current age is \( A \):
    • Age \( n \) years ago: \( A - n \)
    • Age \( n \) years from now: \( A + n \)
  • Forming Equations: Translate phrases involving relationships between ages (like "twice as old", "sum of ages", "ratio of ages") into mathematical equations.
  • System of Linear Equations: Most age problems with two or more people at different times will result in a system of two or more linear equations.
  • Solving Techniques: Standard methods for solving systems of equations include:
    • Substitution: Solve one equation for one variable and substitute that expression into the other equation.
    • Elimination: Multiply equations by constants so that one variable cancels out when the equations are added or subtracted.

Mastering the translation of word problems into mathematical equations is crucial for solving age problems. Careful reading of the problem statement is essential to correctly identify the relationships between the ages at the specified times.

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Similar Questions

  1. Seven years from now Virat will be twice as old as Mohinder. Five years ago, Mohinder’s age was one year less than 2/5 of Virat’s age. What is Virat’s present age?

  2. Three years from now Dhahiri’s age will be eight years less than twice Eunice’s age. The sum of their present ages is 61 years. What is Dhahiri’s present age?

  3. The sum of the present ages of two cousins is 46 years. Eight years ago, the elder one was twice as old as the younger one. What is the present age of the elder cousin?

  4. Present ages of Sai and Satheesh are in the ratio of 5 : 4 respectively. Three years hence, the ratio of their ages will become 11 : 9 respectively. What is Satheesh’s present age in years?

  5. Krish is 5 years younger than Parthiv. Eight years ago, three times the age of Krish was 10 more than twice the age of Parthiv. Find Krish’s present age.

  6. The difference between Peter and Preeti’s ages is 5 years. When they married each other 35 years ago, 4 times Peter’s age was the same as 5 times the age of Preeti’s. What is the current sum of their ages?

  7. Rathin is now 16 years old while his cousin is 7 years. After how many years will Rathin’s age be 1.5 times that of his cousin?

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  9. Ram’s father is twice as old as Ram is. Eight years ago, the age of Ram’s father was 2.5 times his age. What is Ram’s current age?

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Important Questions from Age

  1. The ages of two persons P and Q are in the ratio 5 : 7. Eight years ago, the ratio of P and Q was 7 : 13. The present ages of P and Q, respectively, are:

  2. One year ago, the ratio of the ages of A and B was 4 : 3. The ratio of their ages, after 7 years from now, will be 9 : 7. What is the present age (in years) of B?

  3. In 8 years, Subhash will be 3 times as old as he is now. After how many years will Subhash be 5 times as old as he is now?

  4. The average ages of parents and two children are 30 years and 8 years respectively. The average age of the family is

    A. 16 years

    B. 19 years

    C. 18 years

    D. 17 years

  5. A father is presently 3 times his daughter’s age. After 10 years he will be twice as old as her. Find the daughter’s present age.

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