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Finding the Fourth Proportional to 478.66, 660.95 and 390.16

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Solution

The fourth proportional to 478.66, 660.95 and 390.16 is: 538.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    478.66 : 660.95 = 390.16 : x
  2. Step 2: Convert to fraction form
    478.66/660.95 = 390.16/x
  3. Step 3: Cross multiply
    478.66x = 660.95 × 390.16
  4. Step 4: Simplify right side
    478.66x = 257,876.25
  5. Step 5: Solve for x
    x = 257,876.25/478.66
  6. Step 6: Final answer
    x = 538.75

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.