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Finding the Fourth Proportional to 918.30, 1,378 and 431.08

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Solution

The fourth proportional to 918.30, 1,378 and 431.08 is: 646.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.30 : 1,378 = 431.08 : x
  2. Step 2: Convert to fraction form
    918.30/1,378 = 431.08/x
  3. Step 3: Cross multiply
    918.30x = 1,378 × 431.08
  4. Step 4: Simplify right side
    918.30x = 594,028.24
  5. Step 5: Solve for x
    x = 594,028.24/918.30
  6. Step 6: Final answer
    x = 646.88

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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.