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Finding the Fourth Proportional to 918.15, 1,375.40 and 429.72

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Solution

The fourth proportional to 918.15, 1,375.40 and 429.72 is: 643.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.15 : 1,375.40 = 429.72 : x
  2. Step 2: Convert to fraction form
    918.15/1,375.40 = 429.72/x
  3. Step 3: Cross multiply
    918.15x = 1,375.40 × 429.72
  4. Step 4: Simplify right side
    918.15x = 591,027.86
  5. Step 5: Solve for x
    x = 591,027.86/918.15
  6. Step 6: Final answer
    x = 643.72

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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.