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Finding the Fourth Proportional to 785.43, 1,178.85 and 420.53

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Solution

The fourth proportional to 785.43, 1,178.85 and 420.53 is: 631.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    785.43 : 1,178.85 = 420.53 : x
  2. Step 2: Convert to fraction form
    785.43/1,178.85 = 420.53/x
  3. Step 3: Cross multiply
    785.43x = 1,178.85 × 420.53
  4. Step 4: Simplify right side
    785.43x = 495,741.79
  5. Step 5: Solve for x
    x = 495,741.79/785.43
  6. Step 6: Final answer
    x = 631.17

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.