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Finding the Fourth Proportional to 785.55, 1,178.93 and 420.64

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Solution

The fourth proportional to 785.55, 1,178.93 and 420.64 is: 631.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    785.55 : 1,178.93 = 420.64 : x
  2. Step 2: Convert to fraction form
    785.55/1,178.93 = 420.64/x
  3. Step 3: Cross multiply
    785.55x = 1,178.93 × 420.64
  4. Step 4: Simplify right side
    785.55x = 495,905.12
  5. Step 5: Solve for x
    x = 495,905.12/785.55
  6. Step 6: Final answer
    x = 631.28

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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.