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Finding the Fourth Proportional to 918.64, 1,378.68 and 406

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Solution

The fourth proportional to 918.64, 1,378.68 and 406 is: 609.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.64 : 1,378.68 = 406 : x
  2. Step 2: Convert to fraction form
    918.64/1,378.68 = 406/x
  3. Step 3: Cross multiply
    918.64x = 1,378.68 × 406
  4. Step 4: Simplify right side
    918.64x = 559,744.08
  5. Step 5: Solve for x
    x = 559,744.08/918.64
  6. Step 6: Final answer
    x = 609.32

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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.