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Finding the Fourth Proportional to 785.55, 1,178.78 and 420.55

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Solution

The fourth proportional to 785.55, 1,178.78 and 420.55 is: 631.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    785.55 : 1,178.78 = 420.55 : x
  2. Step 2: Convert to fraction form
    785.55/1,178.78 = 420.55/x
  3. Step 3: Cross multiply
    785.55x = 1,178.78 × 420.55
  4. Step 4: Simplify right side
    785.55x = 495,731.09
  5. Step 5: Solve for x
    x = 495,731.09/785.55
  6. Step 6: Final answer
    x = 631.06

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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.