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Finding the Fourth Proportional to 786.63, 1,178.91 and 420.63

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Solution

The fourth proportional to 786.63, 1,178.91 and 420.63 is: 630.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.63 : 1,178.91 = 420.63 : x
  2. Step 2: Convert to fraction form
    786.63/1,178.91 = 420.63/x
  3. Step 3: Cross multiply
    786.63x = 1,178.91 × 420.63
  4. Step 4: Simplify right side
    786.63x = 495,884.91
  5. Step 5: Solve for x
    x = 495,884.91/786.63
  6. Step 6: Final answer
    x = 630.39

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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.