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Finding the Fourth Proportional to 785.60, 1,178.40 and 420.20

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Solution

The fourth proportional to 785.60, 1,178.40 and 420.20 is: 630.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    785.60 : 1,178.40 = 420.20 : x
  2. Step 2: Convert to fraction form
    785.60/1,178.40 = 420.20/x
  3. Step 3: Cross multiply
    785.60x = 1,178.40 × 420.20
  4. Step 4: Simplify right side
    785.60x = 495,163.68
  5. Step 5: Solve for x
    x = 495,163.68/785.60
  6. Step 6: Final answer
    x = 630.30

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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.