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Finding the Fourth Proportional to 612.40, 918.90 and 287.72

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Solution

The fourth proportional to 612.40, 918.90 and 287.72 is: 431.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    612.40 : 918.90 = 287.72 : x
  2. Step 2: Convert to fraction form
    612.40/918.90 = 287.72/x
  3. Step 3: Cross multiply
    612.40x = 918.90 × 287.72
  4. Step 4: Simplify right side
    612.40x = 264,385.91
  5. Step 5: Solve for x
    x = 264,385.91/612.40
  6. Step 6: Final answer
    x = 431.72

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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.