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Finding the Fourth Proportional to 918.72, 1,377 and 431.64

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Solution

The fourth proportional to 918.72, 1,377 and 431.64 is: 646.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.72 : 1,377 = 431.64 : x
  2. Step 2: Convert to fraction form
    918.72/1,377 = 431.64/x
  3. Step 3: Cross multiply
    918.72x = 1,377 × 431.64
  4. Step 4: Simplify right side
    918.72x = 594,368.28
  5. Step 5: Solve for x
    x = 594,368.28/918.72
  6. Step 6: Final answer
    x = 646.95

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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.