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Finding the Fourth Proportional to 478.35, 715.95 and 390.99

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Solution

The fourth proportional to 478.35, 715.95 and 390.99 is: 585.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    478.35 : 715.95 = 390.99 : x
  2. Step 2: Convert to fraction form
    478.35/715.95 = 390.99/x
  3. Step 3: Cross multiply
    478.35x = 715.95 × 390.99
  4. Step 4: Simplify right side
    478.35x = 279,929.29
  5. Step 5: Solve for x
    x = 279,929.29/478.35
  6. Step 6: Final answer
    x = 585.20

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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.