Math Problem Statement

Pranay, Rohit, and Qureshi bought some marbles. If Rohit gave 2 marbles to Qureshi, the ratio of the number of marbles with Pranay, Rohit, and Qureshi would become 1:3:3. Had Rohit given 2 marbles to Pranay, then the ratio of the number of marbles with them would have become 2:3:2. What will be the ratio of the number of marbles with Pranay, Rohit, and Qureshi when 4 marbles are added to the number of marbles each one of

them already had?

Solution

Let's denote the number of marbles with Pranay, Rohit, and Qureshi as PP, RR, and QQ respectively.

Step 1: Set Up Equations Based on Given Ratios

First scenario (Rohit gives 2 marbles to Qureshi): After giving 2 marbles to Qureshi:

  • Pranay: PP
  • Rohit: R2R - 2
  • Qureshi: Q+2Q + 2

The new ratio becomes: PR2=13andR2Q+2=33\frac{P}{R - 2} = \frac{1}{3} \quad \text{and} \quad \frac{R - 2}{Q + 2} = \frac{3}{3}

From the first part: 3P=R2R=3P+2(1)3P = R - 2 \quad \Rightarrow \quad R = 3P + 2 \quad \text{(1)}

From the second part: R2=Q+2Q=R4(2)R - 2 = Q + 2 \quad \Rightarrow \quad Q = R - 4 \quad \text{(2)}

Second scenario (Rohit gives 2 marbles to Pranay): After giving 2 marbles to Pranay:

  • Pranay: P+2P + 2
  • Rohit: R2R - 2
  • Qureshi: QQ

The new ratio becomes: P+2R2=23andR2Q=32\frac{P + 2}{R - 2} = \frac{2}{3} \quad \text{and} \quad \frac{R - 2}{Q} = \frac{3}{2}

From the first part: 3(P+2)=2(R2)3P+6=2R42R=3P+10R=3P+102(3)3(P + 2) = 2(R - 2) \quad \Rightarrow \quad 3P + 6 = 2R - 4 \quad \Rightarrow \quad 2R = 3P + 10 \quad \Rightarrow \quad R = \frac{3P + 10}{2} \quad \text{(3)}

From the second part: 2(R2)=3Q2R4=3QQ=2R43(4)2(R - 2) = 3Q \quad \Rightarrow \quad 2R - 4 = 3Q \quad \Rightarrow \quad Q = \frac{2R - 4}{3} \quad \text{(4)}

Step 2: Solve the System of Equations

Substituting equation (1) into equations (2) and (3):

  • From (2): Q=(3P+2)4=3P2Q = (3P + 2) - 4 = 3P - 2

  • Substituting RR from (1) into (3): 3(3P+2)+10=2R9P+6+10=2(3P+2)3(3P + 2) + 10 = 2R \quad \Rightarrow \quad 9P + 6 + 10 = 2(3P + 2) 9P+16=6P+43P=12P=4(impossible)9P + 16 = 6P + 4 \quad \Rightarrow \quad 3P = -12 \quad \Rightarrow \quad P = -4 \quad \text{(impossible)}

Step 3: Verify Correctness and Re-setup Equations

Returning to ratios and verifying, let's isolate RR and QQ: Using equation (1): Substituting RR in QQ: Q=R4=(3P+2)4=3P2Q = R - 4 = (3P + 2) - 4 = 3P - 2

Using the second scenario: Substituting into (4): Q=2(3P+2)43=6P+443=6P3=2PQ = \frac{2(3P + 2) - 4}{3} = \frac{6P + 4 - 4}{3} = \frac{6P}{3} = 2P

Step 4: Find PP, RR, QQ

Setting the equations for QQ: From both equations: 3P2=2PP2=0P=23P - 2 = 2P \quad \Rightarrow \quad P - 2 = 0 \quad \Rightarrow \quad P = 2

Then: From (1): R=3(2)+2=6+2=8R = 3(2) + 2 = 6 + 2 = 8 From (2): Q=R4=84=4Q = R - 4 = 8 - 4 = 4

Thus: P=2,R=8,Q=4P = 2, \quad R = 8, \quad Q = 4

Step 5: Calculate Ratios After Adding 4 Marbles

Now when each has 4 additional marbles:

  • Pranay: 2+4=62 + 4 = 6
  • Rohit: 8+4=128 + 4 = 12
  • Qureshi: 4+4=84 + 4 = 8

Final Ratio

Thus, the new ratio is: 6128=6:12:8=3:6:4\frac{6}{12}{8} = 6:12:8 = 3:6:4

Conclusion

The final ratio of the number of marbles with Pranay, Rohit, and Qureshi after adding 4 marbles each is: 3:6:43:6:4

Would you like more details or have any questions? Here are some related questions:

  1. What happens if Rohit gives 3 marbles to Qureshi instead?
  2. How would the ratios change if Pranay had started with 5 marbles?
  3. Can we find the total number of marbles they originally had?
  4. What would be the ratio if all three gave away 2 marbles each?
  5. How many marbles does each person have if we only change the addition to 3 marbles?

Tip: Always keep track of how many marbles each person starts with when solving ratio problems; it can help prevent confusion!

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Math Problem Analysis

Mathematical Concepts

Algebra
Ratios
Systems of Equations

Formulas

Setting up ratios: a:b implies a = k * b for some constant k
Systems of equations solution methods (substitution)

Theorems

Properties of ratios
Basic algebraic manipulation in systems of equations

Suitable Grade Level

Grades 9-10